I say listen to some new music, whenever I'm down I can always find a few of those special tracks that make everything better. Maybe go and watch Amelie, perfect film....I think movies and music are the best bet tho, they always cheer me up coz they tend to change your state of mind..
And, well listen to this song, its uplifting and meloncholy I say...
http://media.putfile.com/heavenly-98 (boards of canada and beck)
you'll see the light soon enough, just takes a little more time to open those curtains again