Yeah I know how this feels. Nothing I ever do is good enough for me. Depression is a tough one. Some things I find which help:
Keep busy!! Even though doing stuff is the last thing you feel like doing. Just do something, anything productive.
Make sure you're getting the right amount of sleep, at the right times. So no less than 6 hours and no more than 10, and they've got to be at night!
Eat properly. I've had to give myself a meal plan lately and it's helped a lot I think.
Plan something for you to look forward to. Always have something in the future to think about, even if it's just a night in watching films, or a walk on the beach.
Light exercise, fresh air and sunlight.
If you are still struggling, perhaps you could go to your GP? I am definitely not one to advocate medication as a means to an ends, but it can help you get out of a rut, and doesn't have to be a long term thing. Depression can sometimes be a chemical imbalance, I know that problems with serotonin production run in my family. Sometimes genetics can really suck.