Friend trouble

I'm having a bit of friend trouble. My friend, let's call her Jane, is completely shutting me out. She always says she is to busy to talk. She won't call or text. She won't email, and she completely blocked me on Facebook. We've been best friends for the past ten years. We were practically sisters. She started getting into weed (which personally I don't really mind, it's just the people she's doing it with) and went into this whole rebel streak. I really don't want to give up on our friendship. We've been through so much together, how do I fix this?