Worried about my friend, what should i do?

okay one of my very best friends in the world, i have known her since i was three, hasn't been in school for literally three months. she has missed a countless number of tests and even midterms!(8 grade) in sixth grade her mom died. in 7 grade at the end of the year she became depressed and cut her self. she went into therapy and skipped school for the rest of the year until finals. at least she ped! but now i am sure she won't p unless she comes to school NOW! the thing is i call her cell phone, text her, call her house phone and comment and message her on myspace but she never answers. and its not like she just isn't there. she goes on myspace everyday and even texts me! but every time i bring it up she disappears! what should i do, any help??