How to Scan & Fix Hard Drives with CHKDSK in Windows

CHKDSK (Check Disk) is a built-in Windows utility that scans your hard drive for file system errors and bad sectors, and attempts to repair them. It can fix issues that cause crashes, slow performance, or files that won’t open. You’ll need to run it from an elevated Command Prompt, and for system drives (usually C:), a restart is often required.

What You’ll Need

Administrator access to the Windows PC
Close any open files and programs (especially on the drive you’re checking)
Time – a full scan on a large or old drive can take several hours

Step-by-Step

Open Command Prompt as Administrator. Click the Start button, type cmd, right-click on “Command Prompt” in the results, and select “Run as administrator”. Confirm any User Account Control prompt.
Identify the drive letter you want to scan (e.g., C:, D:, E:). You can check in File Explorer under “This PC”.
Run a basic scan (read-only). Type chkdsk [drive letter]: (for example, chkdsk C:) and press Enter. This reports errors but doesn’t fix them – useful for a quick health check.
Run a full repair scan. To fix errors, type chkdsk [drive letter]: /f and press Enter. The /f flag tells Windows to fix any errors it finds.
Add bad-sector scanning. For a more thorough check, use chkdsk [drive letter]: /f /r. The /r flag locates bad sectors and recovers readable information, and it implies /f.
Handle a locked drive. If you’re scanning the system drive (usually C:), Windows will say it can’t lock the drive and ask if you want to schedule it for the next restart. Type Y and press Enter.
Restart your PC if prompted. The scan will run before Windows fully loads – you’ll see a blue screen with a progress percentage. Let it complete; don’t interrupt it.
Review the results. After the scan finishes, the command prompt window will show a summary. If you restarted, the results appear in the Event Viewer (Windows Logs → Application, source “Wininit”) after you log back in.

Common Mistakes

Not running as administrator. CHKDSK requires elevated privileges; otherwise you get an “Access denied” error.
Using the wrong drive letter. Double-check you’re scanning the drive you intend to – scanning the wrong drive wastes time.
Skipping the /r flag. Running only /f won’t check for bad sectors, which are a common sign of physical drive issues.
Interrupting a scheduled scan. Pressing a key or powering off during a CHKDSK on boot can cause additional file system damage.
Assuming CHKDSK fixes everything. If the drive has physical damage, CHKDSK can only mark bad sectors; it cannot repair hardware failures.

Tips

Use chkdsk /? to see all available options, such as /x to force-dismount the drive before scanning.
For SSDs, CHKDSK is generally safe but less necessary – it won’t “fix” the wear-leveling issues that affect solid-state drives. Still run it if you suspect file system corruption.
Run CHKDSK regularly (e.g., every few months) on older mechanical drives to catch issues early.
Back up important data before running a repair scan – while rare, the repair process can sometimes make files inaccessible if the file system is severely damaged.
If you have a very large drive, run CHKDSK overnight or when you don’t need the PC, as it can take hours.

Troubleshooting

“Access denied” error: You’re not running as administrator. Close the Command Prompt and reopen it with “Run as administrator”.
“The type of the file system is RAW” or “CHKDSK is not available for RAW drives”: This indicates the file system is corrupted or the drive is unformatted. Try recovery software first, but you may need to format the drive (which erases data).
CHKDSK gets stuck at a certain percentage: This can happen on drives with many bad sectors. Wait at least an hour; if it’s still stuck after several hours, you may need to force-stop it (though this can cause further issues). Try running chkdsk /f first, then /r separately.
Scan completes but errors persist: Run CHKDSK again with /f /r. If the same errors reappear, the drive may be failing physically – back up your data immediately and consider replacing the drive.
Windows won’t boot to run the scan: Boot from a Windows installation USB, choose “Repair your computer”, then go to Troubleshoot → Advanced Options → Command Prompt, and run CHKDSK from there.

Frequently Asked Questions

Does CHKDSK delete my files?

No, CHKDSK does not delete your files. It repairs file system errors and recovers readable data from bad sectors. However, if a file is severely corrupted, it may be moved to a folder like found.000 on the drive root – you can try to open those files, but they may be damaged.

How long does CHKDSK take?

It varies widely – from a few minutes on a small, healthy drive to several hours on a large or failing drive. The /r scan is the slowest because it reads every sector.

Can I use my computer while CHKDSK is running?

No, especially if it’s running during boot. You should not use the computer or open any programs on the drive being scanned, as that can interfere with the process.

What’s the difference between /f and /r?

/f fixes file system errors (like bad file records). /r does everything /f does, plus it scans for bad sectors and attempts to recover data from them. Use /r for a thorough check.

Is CHKDSK safe for SSDs?

Yes, it’s safe, but it’s less useful. SSDs don’t have mechanical parts, so bad sectors are handled differently. Running CHKDSK occasionally is fine, but don’t expect it to improve SSD performance.

Why does CHKDSK say I need to restart?

Windows can’t lock the system drive while it’s in use, so it schedules the scan to run at the next restart, before the operating system fully loads. This is normal.

General steps for current mainstream versions; menus can differ by device and version. See the disclaimer or report an error.

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