How do I pull myself out of this? I feel so depressed.?

I feel so depressed I can't take it anymore. I've been sitting here crying for days. Not, nonstop, but a lot. Or, when I quit crying I get angry. Like really, unreasonably angry. I can't seem to do anything but those two things. I have one friend I could talk to about this, but he's ... not even listening when I try to say something's wrong. I don't know what to do.