My girlfriend wont talk to me and wont tell me why, what should I do?

Tell her that she's acting very immature and if she has a problem with you that she needs to sit down with you and discuss it like two mature adults, no yelling or swearing involved, just listen to each others criticisms and try to work on those things to build a stronger relationship. If she won't sit down with you and work things out, then tell her you have better things to do than be stuck in a one way relationship with someone who won't talk to you and you might as well dump her if she's going to treat you this way.