- Did you get the same message if you plug the defective flashdrive on another computer/laptop? Kung hindi, copy off the files to the working laptop/computer, reformat the flashdrive and copy back.
- Filesystem on the USB flashdrive got corrupted... Baka nahugot while accessing the drive kaya na-corrupt yung filesystem. Try Norton Systemworks Disk Doctor or run chkdsk.
- Possible viral-infection? Na-scan mo na yung flashdrive using an up-to-date AV? Kung wala, try using housecall65.trendmicro.com. Libreng online AV scanning tool. Di cya memory resident program so it should not take place of a full version of an anti-viral software.
Possible ODD solution:
As funny as it sounds but it works for diskettes back then sa trabaho... Untested ko pa sa Flashdrive though... It doesn't hurt to try since you have nothing to lose.
When prompted to format the flashdrive:
- Do not cancel the Format screen. Remove defective flashdrive
- Plug-in another flashdrive that's empty and have the OS format it. It should be the same drive letter & name. Might help kung identical capacity & brand.
- Afterwards, plug back the defective flashdrive and see if it recognizes the files.
This actually works on diskettes at work back then. I don't have a good explanation for it but all I know it works. It should be the same for flashdrives.
Once you access the flashdrive properly, copy off all the files (sometimes have to do it in batches to work) and discard the unit. If you want to tempt fate, format & see if it still works. I advise not to save important files there at baka mangyari ulit yung problema.
Hope this helps. Good luck.