When ever I feel down I just focus on what has made me upset or angry. Then with all of this passion I sit down and write. When I do this I produce my best work and am at my zenith.
i sulk the i watch friends then i watch movies. if nothing else helps i talk to my mother.. that always work..
Just wait for it to pass really. Try to get on with whatever I have to do. Maybe find someone to talk to. Never about my problems though. Just talking to someone about anything helps. That and the usual stuff - watching a movie, reading a book, drinking.
Drink. Not to sound alcoholic or whatever, but is is my go-to when I feel down, alone, bored or finding it hard to sleep. I don't do it on a daily tho.
Watch or listen to Eckhart Tolle. If you haven't heard of him I highly suggest looking him up - and don't let his affiliation with Oprah turn you off before you give him a chance.