Magic should be a last resort, and I don't know what you believe it would achieve in the first place. It would be nice if you gave more information; what is the situation and why have you turned to magic?
If you believe she is in immediate danger of hurting herself, or others, and potenally dieing then you should contact medical/police services to help her.
If your friend is hurting themself, the best thing to do would to talk to someone and make sure that the friend is ok.
Depending on your age, try telling a parent, school counselor, family member, or if is dire... please call the authorities for help.
Their safety is what matters at the end of the day.