16 GB Thumb Drive Becomes Write Protected - Cannot Format

This isn't specifically Windows 7, but I hope I have more possibilities with Windows 7. My thumb drive, which I hate to have to throw away, has become write-protected. It's a 16 GB thumb drive, so nothing to toss easily. It has no physical switch on it. I read about all sorts of solutions, like low-level format or registry editing. Nothing works. I always come back to square one: Can't format because of write-protection. Registry doesn't do a thing. I also found out that there is a virus on it. Maybe it caused the problem. However, the virus program can't remove it, because of the write-protection or because it is a 'non-local disk'. Vicious circles...