Many flash devices are designed to go into a read-only mode when they fail. That way you can still get your data off the drive, without risk of destroying the data by trying fix the drive.
32GB flash drives are currently selling for about $10. If your drive doesn't have a write-protect switch, it's probably a better use of your time to just buy a new drive, copy your data over, and move on with life; rather than spend time trying to figure out what's wrong with this one.