Our daughters years from 13-16 were the worst years of my life. It started with having a bad friend as described above. She was constantly doing things behind our back and when we disciplined her she threatened to run away and she was dead serious. At that point we put her in one of those wilderness programs in Utah in the middle of nowhere. She spent about nine months in the program which was very structured and highly disciplined. We were in constant touch with her counselors and visited her about once every month or two. We checked it out pretty thoroughly before committing her to it.
When we brought her home, she had a few minor setbacks but had turned the corner. By her senior year she was a different kid and now is married and a great mother. She now thanks us for doing what we did. I often wonder if we had kept her at home what would have happened. I think we would have still gotten through it, but it would have been hell.
Im not sure what advice I can give you as some kids at that age are almost impossible to communicate with. Their friends become more important to them than you are. I do know that you need to maintain reasonable discipline or it will only get worse. Try to keep her active in things she likes to do with kids that are a good influence. A counselor with or without her can likely give you some good advice.