Find something that means something to you. Find something you are good at or enjoy doing. I remember in 7th grade that I had depression and I felt like that. Then I took up an art class, and I found a new reason for living. Eventually, I found a lot of hobbies that made me happy, and started wanting to be friends with people. These things help me cope with school, life, and everything else. They gave me something to work for, and something to be proud of. If you can even get one hobby, it will make you so much happier. (but make sure that YOU choose it, and YOU enjoy it).
Oh, and like another poster said, it is good to let it out sometimes. Heck, I wish I had found it before now.
Hope it gets better.