Use the operating system’s built-in checker, but protect your files first. On Windows, identify the USB drive’s letter in File Explorer and run chkdsk X: /f from Terminal or Command Prompt. On a Mac, open Disk Utility, choose View > Show All Devices, and run First Aid from the lowest-level volume upward to the physical device. These procedures can repair filesystem and directory-structure errors; neither one proves that the flash memory hardware is healthy.
Copy any readable, important files to another disk before starting. Repair tools modify damaged filesystem metadata, and a repair can expose or worsen data loss when the drive is already failing.
As an Amazon Associate I earn from qualifying purchases.
What these checks can—and cannot—tell you
A USB flash drive has two different kinds of problems: logical damage to its filesystem and physical or electronic failure of the storage itself. Windows CHKDSK and macOS Disk Utility First Aid address the first category.
- Filesystem damage: broken directory entries, allocation information, volume structures, or other formatting metadata.
- Hardware failure: worn-out flash cells, a failing controller, unstable power, a damaged connector, or a device that disconnects during reads.
A successful scan means the tool found no repairable problem in the structures it checks. It does not certify the drive’s remaining lifespan or guarantee that every file is readable. Apple specifically warns that Disk Utility cannot detect or repair every problem a disk may have.
#1 Best Overall
- USB-C 2-in-1 storage OTG: The Lexar JumpDrive Dual Drive D40E features USB Type-A and Type-C connectors in a slim, portable form factor for easy device compatibility
- Transfer speeds up to 100MB/s: Based on internal testing, performance may vary depending upon the host device, interface, and usage conditions. 1MB=1,000,000 bytes
- Plug and Play: Widely compatible with USB Type-C smartphones, tablets, laptops, Macs, and traditional Type-A devices, no software installation required. The 360° swivel design allows for easy switching between connectors without the hassle of losing a cap
- Durable & Compact: The Lexar D40E USB memory stick features a metal enclosure, withstands temperatures from 0° to 50° C (32°F to 122°F), and is lightweight at 26g with dimensions of 70.4 x 16.9 x 11.7mm
- Security & Warranty: Securely protects files using an advanced security software solution with 256-bit AES encryption. Backed by a Lexar 3-year limited warranty
Think of these utilities as consistency checks for the way files are cataloged, not as a complete health report for the memory chips. A drive can pass a directory check and still fail later, and a drive with a damaged directory can still contain recoverable files. That distinction determines what you should do after the result.
Before you run any repair
Copy files while the drive is still readable
Open the drive normally and copy irreplaceable documents, photos, and other files to an internal disk or a second, known-good drive. Start with the most valuable files. If copying produces read errors, repeated disconnects, or very slow progress, stop repeatedly retrying the same damaged file and preserve everything else that can be read.
Make the copy before launching a repair, not after. A repair may rewrite directory records or allocation information, so the state you see afterward may differ from the state that contained the most recoverable metadata. If the drive has several folders, copy the highest-priority material first and verify that important files open from the destination.
What’s actually slowing this PC down?
Pick the symptom - the matching free tool is one click away.
Do not format or erase a drive you still need
Formatting, erasing, or initializing a USB drive destroys its existing filesystem structures. Those actions are appropriate only after you have a backup or have deliberately decided that the contents no longer matter. A new drive is not a method for recovering data from the old one.
Close applications and safely eject other than during the check
Close files and applications that use the USB drive. When you are finished, eject it through the operating system rather than pulling it out while writes may still be pending. Microsoft’s guidance is to safely remove USB flash drives and external hard drives before disconnecting them.
Do not unplug the drive while CHKDSK or First Aid is actively reading or changing it. An interruption can leave filesystem metadata only partly updated. Keep the computer connected to reliable power, especially when working with a drive that already disconnects unexpectedly.
Check and repair a USB drive on Windows
1. Identify the correct drive letter
- Connect the flash drive and wait for Windows to recognize it.
- Open File Explorer and select This PC.
- Find the removable drive and note its letter, such as
E:orF:. Check its label and approximate capacity so you do not select an internal disk by mistake.
The command must target the USB volume’s actual letter. Substituting the wrong letter can check or modify a different disk. If the drive appears more than once, use the entry whose capacity and label match the physical stick you connected.
2. Open an elevated command window
Open Windows Terminal or Command Prompt. If Windows asks for administrator permission, approve it. An elevated window avoids permission errors when the checker needs access to the volume.
3. Run CHKDSK with logical repair
Enter the following command, replacing X: with the letter you recorded:
Rank #2
- High-speed USB 3.0 performance of up to 150MB/s(1) [(1) Write to drive up to 15x faster than standard USB 2.0 drives (4MB/s); varies by drive capacity. Up to 150MB/s read speed. USB 3.0 port required. Based on internal testing; performance may be lower depending on host device, usage conditions, and other factors; 1MB=1,000,000 bytes]
- Transfer a full-length movie in less than 30 seconds(2) [(2) Based on 1.2GB MPEG-4 video transfer with USB 3.0 host device. Results may vary based on host device, file attributes and other factors]
- Transfer to drive up to 15 times faster than standard USB 2.0 drives(1)
- Sleek, durable metal casing
- Easy-to-use password protection for your private files(3) [(3)Password protection uses 128-bit AES encryption and is supported by Windows 7, Windows 8, Windows 10, and Mac OS X v10.9 plus; Software download required for Mac, visit the SanDisk SecureAccess support page]
chkdsk X: /fFor example, if File Explorer shows the USB drive as D:, run:
chkdsk d: /fMicrosoft documents chkdsk d: /f as the pattern for checking and fixing errors. Without /f, CHKDSK reports errors but does not correct them. The /f option repairs logical disk errors.
Quick wins for a faster PC:
Fix the driver behind crashes, sound loss and screen glitchesFind Drivers →Repair Windows errors before they cause bigger problemsFix Now →Scan for outdated or missing drivers - takes under a minuteDriver Scan →Use the colon exactly as shown and keep the space before the switch. The command checks the volume represented by that letter; it is not a general scan of every disk attached to the computer.
4. Allow Windows to lock the volume
CHKDSK needs access that locks the volume while it makes repairs. If Windows says the volume is in use or cannot be locked, close every File Explorer window and application using the drive, then run the command again. Do not disconnect the USB drive during the scan.
Programs that commonly keep a volume open include document editors, media players, backup software, antivirus scans, indexing services, and a second terminal window. If the lock still fails after you close visible programs, restart Windows and run CHKDSK before opening files from the USB drive.
Read the complete status report when the command finishes. It will indicate whether Windows found errors, corrected them, or found no problems. Save the text or take a screenshot if you need to document the result. A report saying that no errors were found applies to the filesystem structures CHKDSK examined, not to every memory cell or controller component.
Recommended Free Tools
5. Use /r only when a deeper read is justified
Microsoft describes /r as checking for physical disk errors and attempting to recover readable data from affected sectors. It performs a more extensive read than a routine logical check and can take substantially longer, particularly on a large or badly damaged volume.
For a normal filesystem check, start with /f. Consider /r when CHKDSK reports read-related problems or when you have a specific reason to examine sectors, and make a backup first whenever the files are still accessible. A completed /r run is not proof that the flash hardware is reliable. It also should not be presented as a guaranteed data-recovery procedure: it can only attempt to recover data that remains readable.
6. Understand the FAT allocation-table warning
Many removable drives use FAT-family filesystems. On those volumes, repairing inconsistent allocation information can change the file allocation table. Microsoft documents that CHKDSK may report lost allocation units and offer to save recovered chains as .chk files.
Rank #3
- What You Get - 2 pack 64GB genuine USB 2.0 flash drives, 12-month warranty and lifetime friendly customer service
- Great for All Ages and Purposes – the thumb drives are suitable for storing digital data for school, business or daily usage. Apply to data storage of music, photos, movies and other files
- Easy to Use - Plug and play USB memory stick, no need to install any software. Support Windows 7 / 8 / 10 / Vista / XP / Unix / 2000 / ME / NT Linux and Mac OS, compatible with USB 2.0 and 1.1 ports
- Convenient Design - 360°metal swivel cap with matt surface and ring designed zip drive can protect USB connector, avoid to leave your fingerprint and easily attach to your key chain to avoid from losing and for easy carrying
- Brand Yourself - Brand the flash drive with your company's name and provide company's overview, policies, etc. to the newly joined employees or your customers
That recovery output does not promise that original filenames, folders, or complete files can be restored. Preserve readable files before repair, and do not treat a successful repair as a substitute for a backup. If Windows offers to save recovered chains, note where it stores them and keep the original drive unchanged after the check if you may need specialist recovery.
The Tool Desk
Outbyte Driver Updater FREEScan for outdated or missing drivers - takes under a minuteDriver Scan →Outbyte PC Repair FREERepair Windows errors before they cause bigger problemsFix Now →Check and repair a USB drive on a Mac
1. Back up readable data
Apple recommends making a current backup before using Disk Utility First Aid because some errors may be unrepairable and files may require recovery. Copy the important contents to another storage device before proceeding.
If Finder stalls on one file, copy other folders first rather than repeatedly forcing the same read. Keep the destination separate from the USB drive so a later repair or disconnection cannot affect both copies.
2. Open Disk Utility
- Open Applications > Utilities > Disk Utility.
- In the menu bar, choose View > Show All Devices when that option is available.
Showing all devices exposes the drive’s hierarchy: one or more volumes, any containers, and the physical USB device. The exact items depend on the drive’s filesystem and partition scheme.
3. Run First Aid from the bottom of the hierarchy upward
- In the sidebar, select the lowest-level volume on the flash drive.
- Click First Aid, then click Run.
- Repeat First Aid for each other volume shown on that physical drive.
- If a container is shown, select it and run First Aid after its volumes.
- Finish by selecting the physical USB device at the top level and running First Aid.
If the sidebar does not show a container, follow the objects that are actually present rather than looking for a missing item. The goal is to check each displayed volume, then its containing structure, and finally the device.
Do these 3 things before closing this tab:
1Fix the driver behind crashes, sound loss and screen glitches2Repair Windows errors before they cause bigger problems3Scan for outdated or missing drivers - takes under a minuteRunning First Aid on only the volume you normally open can leave an error in a container or partition map unchecked. Working upward gives each layer a chance to validate the structures below it. The names and number of layers vary, so use the hierarchy Disk Utility displays rather than assuming every flash drive has the same layout.
4. Interpret the result
First Aid checks and can repair problems related to formatting and directory structure. A message that the operation completed successfully means that First Aid finished its checks; it does not certify the flash memory, controller, connector, or every file on the drive.
If First Aid reports that it cannot repair the disk, preserve the backup you made and avoid repeatedly launching repairs on irreplaceable data. Apple’s guidance distinguishes repairable formatting problems from disks that may need service or replacement. Do not erase the drive simply to make the warning disappear if you still need its contents.
Windows and Mac checks compared
| Question | Windows | Mac |
|---|---|---|
| Built-in utility | CHKDSK in Windows Terminal or Command Prompt | Disk Utility First Aid |
| Primary scope | Filesystem and volume errors | Formatting and directory-structure errors |
| Repair action | /f is required to correct logical errors |
First Aid is the check-and-repair workflow |
| How to target the drive | Use the USB volume’s File Explorer letter, such as E: |
Select the drive’s volumes, containers, and physical device in the sidebar |
| Hardware diagnosis | Not a complete flash-memory health test | Not a complete flash-memory health test; Apple says not all disk problems can be detected or repaired |
| Data-preservation risk | FAT repairs can alter the allocation table and may produce .chk recovery files |
Repair can fail or leave files needing recovery, so Apple recommends a backup first |
The platforms use different interfaces, but the safe order is the same: identify the correct device, copy readable data, run the built-in consistency check, and judge the drive by its behavior afterward. Neither utility replaces a backup strategy or a dedicated professional recovery process for irreplaceable data.
Rank #4
- GOOD VALUE PACKAGE - 1 Pack 32GB Memory Stick USB 2.0 Flash Drives with great cost performance and high quality.
- BIG CAPACITY - The available capacity: 29.10GB-29.8GB, You can save the data of movies, music, photos, designs, programs, manuals, handouts in a high speed.Good performance in digital data storing, transferring and sharing with families, friends, workmates, clients and machines.
- EASY TO USE & PLUG AND WORK - Support windows 7 / 8 / 10 / Vista / XP / 2000 / ME / NT Linux and Mac OS, Compatible with USB2.0 and below.
- TWISTTURN DESIGN & EASY CARRY - The metal clip rotates 360° round the ABS plastic body which with rubber oil skin feeling finish. The capless design can avoid lossing of cap, and providing efficient protection to the USB port.
- WARRANTY & SUPPORT - SIMMAX logo is laser printed on the USB connector surface, our products are of good quality and we promise that any problem about the product within one year since you buy.
What to do when the check finds errors
If the repair succeeds and the drive works normally
Open several folders and files, then copy the entire contents to a separate backup. A repaired directory does not make the USB drive a dependable sole copy of your data. Use safe removal before unplugging it. Continue watching for new copy failures or unexplained disconnects rather than returning immediately to using it as the only storage location.
If errors return after repair
Repeated corruption points beyond a one-time directory problem. Copy the data while possible, stop using the drive for important work, and plan to replace it. Re-running the same repair over and over can alter damaged metadata without restoring missing content.
If Windows cannot lock the drive
- Close documents, media players, backup tools, antivirus scans, and File Explorer windows that are open on the USB volume.
- Run CHKDSK again from an elevated Terminal or Command Prompt.
- If another process continually reopens the drive, restart Windows and retry before opening files from it.
Do not force a disconnection while Windows is writing or while CHKDSK is active.
If First Aid cannot repair the disk
Keep the backup or copied files in a safe location. Do not erase the drive merely to remove the error message if its contents matter. If the data is irreplaceable and unreadable, stop experimenting with repairs and consider professional data-recovery help rather than assuming another First Aid run will restore it.
Free tools Windows power users keep installed
One-click scans. No signup required.
When the USB drive is missing
Windows checks
Confirm that the drive appears in File Explorer and that you have recorded the correct letter. Try a different USB port and, if available, another computer. If Windows cannot see a volume at all, CHKDSK cannot be pointed at it by letter; the problem may involve the connection, partition information, or hardware.
Do not assign a new letter, initialize, or format the device merely because it is absent from This PC when its data matters. First establish whether another port or computer detects it and whether the original connection is secure.
Mac checks
If the drive does not appear in Disk Utility, Apple advises checking the external drive’s cable or connector, its connection, and its power. Try another port or computer if practical. A device absent from Disk Utility cannot be repaired through First Aid until the Mac can detect it.
If it appears in Disk Utility but not on the desktop, inspect the sidebar and the hierarchy before assuming the hardware is dead. If it is visible but reports that it is about to fail, prioritize copying data and replacement rather than repeated repair attempts.
Outdated Drivers Are Slowing You Down
One free scan finds every outdated or missing driver and matches the right update for your exact hardware.Free scan · exact hardware matchWindows Errors? Fix Them Before They Spread
Repair common Windows errors and clear accumulated junk for a smoother, more stable PC - no reinstall needed.Free scan · no reinstallSigns that the flash drive itself may be failing
- The drive disconnects or reconnects during ordinary file access.
- Files that worked previously become unreadable, or new copies fail verification.
- Capacity or volume information changes unexpectedly.
- Both operating systems report errors, or repairs succeed only temporarily.
- The operating system explicitly reports that the disk is about to fail.
When a Mac reports that a disk is about to fail, Apple’s advice is to back it up and replace it. Treat an equivalent pattern on Windows as a reason to retire the drive after preserving the data, not as an invitation to keep testing it indefinitely. A replacement drive solves the storage problem going forward; it does not recover files that were never copied from the failing device.
Best Value
- 【16GB Flash Drive】USB flash drives with 16GB capacity, meet your needs of daily use on work, school, home and travelling for photos, music, videos, files storage and transfer. IMEASON thumb drives can be used to store different files, easy to data backup.
- 【Metal Swivel Cap Design】USB thumb drive is metal swivel cover provides extra protection for the usb thumbdrive connector, no usb drive cap to lose; keychain design makes it easier to carry without worrying lose it.
- 【Wide Compatibility】USB drive supports Windows 7/8/10/11 / Vista / XP / Unix / 2000 / ME / NT Linux and Mac OS, also Supports USB 2.0 and 1.1 ports. USB Stick support TV, desktop, notebook computer, car, audio and other device. The USB Memory Stick is your great data storage and transfer companion with traveling and working.
- 【Easy to use】usb memory stick is plug and play without any software installation. Just simply plug the Flashdrive into the port of your USB-compatible devices such as computer, laptop to start data storage or transmission.
- 【What You Get】16 GB USB Flash Drive Thumb Drive, The default format of the usb storage flash drive is FAT32.
Safe removal after checking
On Windows, use the taskbar’s Safely Remove Hardware control or the drive’s Eject command in File Explorer, and wait for confirmation before unplugging it. Microsoft notes that Windows can use different removal policies:
- Quick removal: write caching is disabled, reducing the need to eject for cached writes, although safe removal is still the prudent habit.
- Better performance: write caching may be enabled, so you must use safe removal before disconnecting.
On macOS, click the drive’s eject icon in Finder’s sidebar and wait until it disappears. If either system says the disk is busy, close the application holding it and try again instead of pulling it out. Safe removal protects against unfinished writes; it does not repair an already damaged filesystem.
A practical decision path
- Can you open the drive? Copy important files immediately.
- Is the drive visible to the operating system? If not, check the port, cable or connector, power, and another computer.
- Does Windows show a drive letter? Run
chkdsk X: /fwith the verified letter. - Does macOS show the drive in Disk Utility? Use Show All Devices and run First Aid from volumes upward.
- Did the tool repair the problem? Test files, create a separate backup, and monitor for recurring errors.
- Does the drive keep failing, disappear, or show a failure warning? Preserve what you can and replace the drive; do not rely on it for important storage.
The built-in checks are appropriate first steps for filesystem corruption, but they are not full hardware diagnostics. Data preservation, correct drive identification, and safe removal matter as much as the command or button you use.
Frequently Asked Questions
Will CHKDSK or First Aid recover deleted files?
No. They repair or verify filesystem and directory structures. CHKDSK may save recovered allocation chains as .chk files on some FAT volumes, but original names, folders, and complete files are not guaranteed. Copy readable data first and use a specialist when the files are irreplaceable.
Should I run CHKDSK with /r first?
Usually start with chkdsk X: /f for logical filesystem errors. Microsoft describes /r as a more extensive check for physical disk errors that attempts to recover readable data, so use it when read-related problems justify the longer, deeper pass and after preserving accessible files.
What if Windows says CHKDSK cannot lock the volume?
Close applications, File Explorer windows, backup tools, media players, and security scans using the USB drive. Run the command again in an elevated Terminal or Command Prompt. If the volume remains busy, restart Windows and retry before opening files.
Why does Disk Utility show volumes, containers, and a device?
They are layers of the drive’s storage hierarchy. With View > Show All Devices enabled, run First Aid on each displayed volume, then its container if present, and finally the physical device. Follow the items actually shown for that drive.
The Tool Desk
Outbyte Driver Updater FREEScan for outdated or missing drivers - takes under a minuteDriver Scan →Outbyte PC Repair FREEClear out junk files and repair common Windows errorsFree Scan →Does a successful check prove the flash drive is healthy?
No. Both utilities focus on filesystem, formatting, or directory structures. A drive can pass while its flash cells, controller, connector, or power stability is deteriorating. Repeated errors, disconnects, unreadable files, or a failure warning are reasons to copy data and replace it.
What should I do if the USB drive is missing?
Check the port, connector or cable, and power, then try another port or computer. CHKDSK needs a visible Windows volume letter, and First Aid needs the device to appear in Disk Utility. Do not initialize or erase a missing drive that contains needed data.
Can I format the drive after an error appears?
Only after you have a verified backup or have intentionally decided to discard its contents. Formatting is destructive and is not a data-recovery step.
Do I still need to eject a USB drive set to Quick removal?
Safe removal remains the prudent habit. Quick removal disables write caching, while Better performance can cache writes and requires safe removal before disconnecting. Wait for the operating system’s confirmation before unplugging.
Quick wins for a faster PC:
Repair Windows errors before they cause bigger problemsFix Now →Fix the driver behind crashes, sound loss and screen glitchesFind Drivers →The Bottom Line
Back up readable files first, then use chkdsk X: /f on Windows or Disk Utility First Aid from volume to device on a Mac. Treat the result as a filesystem check, not a hardware guarantee. If errors return, the drive disconnects, files remain unreadable, or the system warns that it is failing, preserve what you can and replace the drive instead of relying on repeated repairs.
Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
