I had experienced that before, and I learned from there. When you use your flash drive, make sure you safely remove the hardware first to avoid data corruption. There is a software I know which can recover accidentally deleted files, but I'm not that sure if it can also help you recover corrupted files from your flash drive. Try to download Data Recovery Pro from recoverfiles.net, there's no harm trying since it's just free. Well, if it can recover deleted files, then I guess it can do the same thing for corrupted ones...