How to reinstall bootcamp assistant

I went into utilities->boot camp assistant->show package contents->contents->Info.plist and changed some of the code and now boot camp assistant always quits unexpectedly when I try to open it. How do I reset this program or what can I do. I am trying to duel boot my mac to run windows 7 premium home 64 bit. I am trying to use a flash drive with windows 7 .iso file but I don't have a clue what I'm doing. I pay $60 for windows and I can't even install it. There are so many errors and stupid formatting crap to do and now boot camp assistant doesn't work. I watched some guy on youtube and followed him exactly and now my bootcamp is messed. Someone please help.