Lost in darkness

The past few weeks I can feel myself slipping back into the dark places of my mind. I don't know why, and I don't know what I can do to pull myself back out again. I want to just stay in my bed all day. I don't want to do anything. I don't have any friends, I haven't in a long time so I cant even force myself to go out and do things with someone, and doing it by myself is just lonely. I am just so lost.