When a USB drive stops working, start with the simplest fixes first
A USB drive that won't read, won't show files, or won't let you write to it usually doesn't need replacement. Most problems come from dirt in the connector, outdated drivers on your computer, file system corruption that Windows or Mac can repair, or a drive that needs reformatting. Before you assume the drive is dead, try cleaning it, checking it on a different computer, and running the built-in repair tools your operating system already has.
If the drive physically broke—cracked connector, bent pins, water damage—repair is rarely worth the cost, but logical failures (the drive works but the files are inaccessible) are often fixable in under an hour. The steps below move from safest to most destructive, so start at the top and work down only if earlier steps don't solve the problem.
Key Takeaways
- Clean the USB connector with a dry cloth or isopropyl alcohol on a cotton swab, since dirt and oxidation are the most common cause of read failures.
- Test the drive on at least one other computer to rule out a driver or software problem on your main machine.
- Use Windows Disk Check or Mac Disk Utility to scan and repair file system errors without losing data in most cases.
- Reformat the drive only as a last resort for logical failures, because reformatting erases all files permanently.
- Physical damage to the connector or circuit board usually cannot be repaired at home and is not worth professional repair costs.
Clean the connector and test on another computer
The connector is the metal part that plugs into your computer, and it collects dust, skin oils, and oxidation over time. This buildup prevents proper electrical contact and is the single most common reason a drive stops being recognized. Unplug the drive and inspect the connector under good light. If you see discoloration, dirt, or a dull finish on the metal, cleaning will often restore it.
Use a dry, lint-free cloth to gently wipe the connector. If that does not work, dampen a cotton swab with isopropyl alcohol (the kind sold for electronics cleaning, usually 90% or higher) and scrub the connector gently for 10 to 15 seconds. Let it air dry completely—at least two minutes—before plugging it in. Do not use water, vinegar, or other liquids.
After cleaning, plug the drive into a different computer. This step is critical because it tells you whether the problem is the drive itself or your computer's USB port, drivers, or settings. If the drive works on another machine, your original computer has a driver issue or a failing USB port. If it does not work on any computer, the drive itself has a problem that cleaning did not fix.
Run Windows Disk Check to find and repair file system errors
If your computer recognizes the drive but you cannot open files, or if Windows says the drive needs to be formatted, a file system error is usually the cause. Windows Disk Check (also called chkdsk) scans the drive for these errors and repairs many of them without erasing your data.
Plug the drive in and note its letter (usually D:, E:, or F:). Open File Explorer, right-click the drive, and select Properties. Click the Tools tab, then click Check under "Error checking." Windows will ask whether you want to scan and fix errors. Select Scan and repair drive. The scan takes 5 to 15 minutes depending on the drive size. Do not unplug the drive or use your computer during the scan.
If Windows says it cannot repair the drive while it is in use, restart your computer. Windows will run the scan before the desktop loads. Let it finish completely. After the scan, try opening your files. If Disk Check found and fixed errors, your files should be accessible again. If the scan finds errors but cannot repair them, or if files are still inaccessible, the drive may need reformatting.
Use Mac Disk Utility to repair a drive on macOS
On a Mac, the Disk Utility tool performs the same function as Windows Disk Check. Plug the drive in, open Applications > Utilities > Disk Utility, and select the USB drive from the list on the left. Click the First Aid button at the top. Disk Utility will scan the drive and attempt to repair any file system problems it finds.
If First Aid reports that the drive cannot be repaired, or if files are still inaccessible after repair, you may need to reformat. Before you do, try the drive on a Windows computer if you have access to one, since sometimes a drive formatted for Windows will show errors on a Mac and vice versa. This test takes only a few minutes and can save you from erasing files unnecessarily.
Reformat the drive only as a last resort
Reformatting erases all files on the drive and rebuilds the file system from scratch. It fixes logical failures that repair tools cannot address, but you lose everything on the drive. Only reformat if the drive is not recognized at all, if repair tools have failed, and if the files on it are either backed up elsewhere or not important.
On Windows, right-click the drive in File Explorer and select Format. Choose a file system (NTFS for Windows, exFAT if you need to use the drive on both Windows and Mac). Give it a name if you want, uncheck "Quick Format" to do a full erase, and click Start. A full format takes 10 to 30 minutes but is more thorough than a quick format.
On Mac, open Disk Utility, select the drive, click Erase, choose a format (Mac OS Extended or APFS for Mac, exFAT for cross-platform use), and click Erase. The drive will be wiped and ready to use in under a minute. After reformatting, test the drive by copying a small file to it and reading it back. If it works, the drive is functional again. If reformatting does not fix the problem, the drive has a hardware failure.
Recognize when hardware damage means the drive cannot be repaired
Physical damage—a cracked or bent connector, water damage, or a visibly damaged circuit board—cannot be fixed at home. Professional data recovery services exist but cost $300 to $3,000 depending on the damage and what data is on the drive. For a consumer USB drive, this cost far exceeds the drive's replacement price.
If the connector is bent or cracked, do not force it into a port, as this can damage your computer's USB port. If the drive has been wet, let it dry completely in a warm, dry place for at least 48 hours before testing it. Water damage sometimes resolves on its own as corrosion dries, but not always. If the drive still does not work after drying, hardware failure is the cause and replacement is your best option.
Prevent future USB drive failures with proper storage and use
USB drives fail less often when you eject them safely before unplugging. On Windows, right-click the drive in File Explorer and select Eject. On Mac, drag the drive to the Trash or right-click and select Eject. Wait for the system to confirm the drive is safe to remove before pulling it out. Unplugging without ejecting can corrupt files or damage the file system.
Store the drive in a cool, dry place and keep the connector covered when not in use. Avoid leaving it in hot cars, humid bathrooms, or places where it might get wet. If you carry it in a pocket or bag, use a small protective case to prevent the connector from bending or collecting dirt. Back up important files to a second location—another drive, cloud storage, or your computer's hard drive. A USB drive is convenient for moving files between computers, but it is not a reliable long-term storage device.
Frequently Asked Questions
Can I recover files from a USB drive that won't open?
Sometimes. If the drive is recognized by your computer but you cannot access the files, running Disk Check or Disk Utility may repair the file system and make files readable again. If the drive is not recognized at all, or if repair tools fail, you would need a data recovery service. For most consumer drives, recovery costs more than the drive itself.
What does it mean if my computer says the drive needs to be formatted?
This usually means the file system is corrupted or unrecognized. Try running Disk Check or Disk Utility first—these tools can often repair the file system without erasing data. If repair fails, reformatting will erase the drive but make it usable again.
Is it safe to use a USB drive after it stops working once?
If the problem was dirt or a file system error that you repaired, yes. If the drive had a hardware failure or physical damage, it may fail again soon. Test it thoroughly with files you have backed up elsewhere before trusting it with important data.
Why does my USB drive work on one computer but not another?
This usually points to a driver issue, a failing USB port on one computer, or a file system mismatch. A drive formatted for Windows may show errors on a Mac. Try the drive on a third computer if possible. If it works on some machines but not others, the drive itself is probably fine—the problem is with one of your computers.
How long should I wait before assuming a wet USB drive is permanently damaged?
Let it dry in a warm, dry place for at least 48 hours. Some water damage resolves as the drive dries completely. After 48 hours, test it on a computer you do not mind risking. If it still does not work, the water likely caused corrosion that cannot be repaired at home.