Headache, constant sadness, loneliness.

I've been having headache and lost interest in studies,daily works.I've difficulty in socializing and I don't have any friends. I talk less to people and useless talks annoy me.I'm short tempered and have thoughts of suicide too.it's been for a very long time.I feel hopeless and worthless.right now I feel as if I've forgotten what I studied during my 1 year course.I've lost interest in almost everything.I'm gaining weight too and constantly feel sleepy.sometimes I'm lost somewhere or I constantly keep looking in one direction but rarely to see anything. I've never socialised since my childhood as I used to live with my grandparents and hardly met people. I get confused while making decisions and end up crying as I feel that I've got no options. I'm not much attached to anybody.sometimes I have constant thoughts of harming myself and even sometimes I do so.I feel that I need psychotherapy.