If it's only been a couple days, I'd visit her and see what's up. If it's been weeks or months, then maybe she's just not interested anymore, or you may have said or did something to upset her. I'd just move on at least until she starts communicating again.
Ask her if anything's wrong... if you have done something wrong so you can determine what the problem is... fuck her brains out if she's cool with it. If she's still acting like how you describe, end it.
Fuck her brains out? I'm a bit too pissed at her for ignoring me to care for that. I'll probably just leave her....unless she convinces me to do otherwise.
If you're pissed let all that stored up anger out on her... that way you're both getting something you want. Sometimes sex fixes problems, man... or at least creates a catalyst to fix the rest of them.