Need antidepressants due to depression.

I used to be a friendly person two years ago. Slowly with time i started being lonely and leaving my friends. Now I have few or none friends. I don't enjoy anything, never want to talk to anyone, always depressed, thinking about past and could not concentrate on studies. Recently I had abortion due to which now I am completely depressed. I never go out, don't attend schools, never want to explain anyone what i am thinking what i am suffering. Always the past eht happend always go around my mind and its too much frustrating. I can't focus on anything be it studies, mobile games or television. Always I be depressed. I can't even think of what to do in future. I know i am ruining my future by not studying but i cant help myself. I am just having suicidal thoughts. Please help me what antidepressants should i take to get out of this.