Joseph pretty much hit it on the head. I haven't heard of anyone doing that type of recovery either and one of the reasons, I believe, is that USB keys (or thumb drives or flash drives or what ever name you use for them) aren't intended to be used for long term storage for the reasons that Joseph mentioned. There aren't any parts inside that can be replaced to recover the files.
If you check around your area, look for someone who specifically performs "data recovery services". Any tech can claim to do this but real recovery services have full clean room facilities for disassembling hard disk drives. All that your neighborhood tech is going to do is hook it up to a working computer and see if he can read any data...maybe (with a hard drive) he'll try rewriting the master boot record but it sounds like you've tried it on other machines already.
True data recovery services aren't cheap. For hard drives it can cost you $100 or more per megabyte...but they frequently have to reconstruct the entire drive. You can't just say..."I need these couple of Excel files." It runs into the thousands really quickly. I've dealt with a place called
HDO here in San Diego who have pulled data off of some severely damaged machines. They might at least be able to tell you if it's possible.
Good luck.