Hard Drive Not Detected
A secondary or additional hard drive that used to appear in File Explorer or Disk Management is no longer showing up, while the computer itself starts and runs normally from its main drive.
Quick answer: If the computer starts fine but a hard drive is missing from File Explorer, it's most often a loose connection, a drive letter that hasn't been assigned, or the drive itself failing. This is different from a boot drive failure, which stops the computer starting altogether.
Likely causes
- A loose power or data cable connection (desktops)
- The drive hasn't been assigned a letter, and still shows in Disk Management without one
- A failing drive that's becoming intermittent before failing completely
- A driver or controller issue, particularly after a Windows update
What you can safely check yourself
- Open Disk Management (search for it in the Start menu) to see whether the drive appears there even if it's not in File Explorer
- For desktops, check the drive's cable connections if you're comfortable opening the case
- Try a different USB port if it's an external or add-on drive
If the drive has important files and it does appear in Disk Management but as "unallocated" or with an unfamiliar status, don't initialise, format or write anything to it — that can overwrite data that might otherwise be recoverable.
When it needs a proper look
If the drive doesn't appear anywhere, including Disk Management, or shows an unfamiliar status and has files that matter, that's worth a proper assessment before attempting anything further.