Lost friendship

I have a very close and special friend and she calls me often on the phone and we support each other with many day to day life issues. We live about 40 minutes apart so don't see each other often. I suffer from anxiety with leaving my house caused from a work place sexual assault, so I am usually home. Lately I have been working very hard to get my life back on track and have started venturing out from my house. I had not heard from her for more than a week as I had been busy out and about. I had called her a couple of times but the phone was engaged. I finally got hold of her and she was really cold and distant towards me. I knew something was wrong 'by the tone of her voice, so I kept asking her what is the matter. She eventually said that when the last time she called me I answered the phone pretending to be a answering machine. I laughed and said I most certainly did not. I assured her I would never do such a thing. She didn't believe me!!!!! And now won't talk to me or private message me back on facebook, or return my texts or return my calls. I called my landline (as that is what she would call me on) and after the phone rings out here is an old voice mail of mine, so obviously this is what she heard. I am lost without my friend.