Get medical and psychological help. Your doctor will possibly prescribe some kind of medication in the short term but will refer you to a mental health specialist to help you get to the bottom of the reasons for your depression and paranoia. Talking to friends will help but in the long run there is NO substitute for professional help.
I would suggest talking to a therapist and looking into med-free ways of coping with your thoughts and feelings. I used to struggle with depression and still do at times. Meeting with my therapist is extremely beneficial.
