I found an old Dreamcast and when I start it up, it goes to the set clock screen but when I press the controller buttons they won't respond. It's not the trnsponder or whatever because its not blown. Is it my controller? If so how can I fix it?

If you got a friend with a dreamcast, maybee try his/her controller out and see if it works...

Im the only person I know who has one.

....then i would buy a used controller somewhere and try it out, you can find one pretty cheap.... just look at a game store or a pawn shop for one.