Mental illness. What problem it is?

Hello doctor.My sister aged 23 now,during 2009 when she studying 10th standard she informed family that Her teacher is used to touch her in bad manner.Her teacher always used to scold her  verbally which was disturbing to her.later on she left education bcoz she was getting irritated by that matter.she used to talk with herself only,always she used to sleep,she always used to through home things out.She thrown her dad mobile in well 3 times stating that dad is not in her side. She used to eat food in very bad manner which potrayed us that she is in bad condition,she never used to groom well,when she is outside home she used to talk with herself only in road.while reading for exams she complained that she remembers that bad matter,she purchased knife for killing her teacher.she her school certificates in her teacher bike stating that she don't need his education more.she never comb her hair.she not do her kitchen and home work.she written in school walls about sir.what problem it is?