How Do I Get Her Back?

This girl, a couple of my guy friends, and I were really close last summer. Me and her would talk on the phone almost non-stop for days at a time.I never told her, or anyone else, that I really had feelings for her. Then a couple months ago she got into this relationship with a total jerk: he plays head games with her, puts her down, smokes pot, and always blows her off for this other girl. Since I knew what a tool this guy was I didn't say anything, but a couple months later now she rarely hangs out with me and my friends anymore and hangs out with a whole group of A-wholes that her and her boyfriend are friends with. I just mis her so much, I still have some unresolved feelings for her, but that doesn't matter I just want one of my friends back. Does anyone have any advice?