Yeah you can fix that, I made the same mistake, accidentally ripping the volume button flex cable from the board. If you know how to solder SMD you're set, but you wouldn't be asking that question.
It's not too difficult to learn, get yourself some very very fine solder, and search youtube for video tutorials [http://www.youtube.com/watch?v=b9FC9fAlfQE|this one is good]. All you have to do is solder the connections back.