Emotional Instability. Please help me.

Hello dear, I understand what a difficult time you are going through. The difficulties that you have mentioned point towards a depressive episode and imply that you will have to seek help. Try to tell your parents about your difficulty in studying and need to meet a counsellor, maybe at your school itself so that it inspires confidence in them. Share your difficulties with the counselor, who may refer you to a psychiatrist or psychologist for further management. If the imposed restrictions by parents are because of some relationship issues,(you mentioned no one trusts you) I would suggest you to focus on studies currently and postpone other things for a later time. In the meanwhile, organise your daily activities in advance, include regular exercise, some meditation, some recreation(music, reading, painting) in it along with studies. Study in short capsules of 30-40 min, with 10 min breaks in between. I hope this helps, but do remember, this is a phase of life and will pass away...hurting yourself by any means will only complicate things and not help. Take care and good luck.