Tree, I have been there many times and the only advice I can give is to just let it go and hope for the best. The ball is in her court, she knows how you feel and it is up to her to make the next move. For me, one-sided friendships are toxic and is one of the issues I work through in therapy. If you don't even know why she isn't talking to you or what you did to deserve it, then chances are you didn't do anything and she is being dramatic. If this is how the "friendship" is going to go then it's not worth it..you are better than that.