Take it one day at a time. I know INTJ's focus a lot on the future, but when you're feeling a little depressed the future can seem bleak and make your even more depressed. We get stuck and forget things wont be the same forever. Actually, I think socialising can help, because it's a distraction and keeps you from over-thinking all the time. Only socialize in a format that you enjoy though, otherwise it will be draining and make things worse. If you don't have any close friends to just hang out with at the moment, do what the other posters said and go to places that interest you, take your ipod with and play happy music. Don't sit at home watching infomercials and listening to depressing stuff. Don't sleep more than necessary just to pass the day, it's very bad for your mood. Go outside and get some sun.
Hope you feel better soon!
Hope you feel better soon!