Why does a drive or file still say unreadable after copying one file back?
Answer
Unreadable usually means the filesystem, cable/adapter, or the specific file is damaged—not that one more copy attempt will always fix it. Test the drive on another cable and computer, copy the needed file to a different healthy disk, and avoid repeated writes if the drive is failing.
Before you start: stop right away if…
- Repeated writes to a failing drive can make recovery harder.
- Reformatting erases remaining recoverable data.
- Ignore popups that demand payment to unlock an unreadable disk.
Follow these steps
Clarify file versus whole-disk failure
Note whether Finder/File Explorer marks one file unreadable or the entire volume needs formatting / cannot be mounted.
You should see: You know if recovery should target one file or the whole drive.
Test with another cable and port
Reconnect the drive using a different cable, USB port, or adapter, then try opening the file or volume again.
You should see: The volume mounts cleanly, or the same unreadable error remains.
Copy readable data to a healthy disk
If the volume mounts, copy needed files to a different internal or external disk—do not keep saving recovered files back onto the suspect drive.
You should see: Critical files are safely elsewhere before further repair.
Decide repair versus replace
For a single corrupted file, obtain another copy from backup or the original source. For a whole disk that stays unreadable, use Disk Utility/CHKDSK only after backup attempts, or replace the drive if it disconnects or makes unusual noises.
You should see: You either open a good copy of the file or have a clear hardware/filesystem next step.
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Extra tips
What to look for: Whether one file or the whole disk is unreadable, exact OS error text, and whether the drive disconnects under load
Before you change anything: Stop writing large amounts of data to a failing drive. Copy anything readable to a different disk first. Try a different cable, port, or adapter. Do not reformat until critical files are recovered or accepted as lost.