The general feeling I get, from reading what people have posted on this site and others, is that most writers get rather caught up in not being able to write. This is something of a Catch 22. If you don't have the need to put pen to paper, then the feeling will remain with you for far longer than it need.
I don't read the works of other writers when the mental ink dries up. It harms my ability to see what I want to write, and gives me the false impression that I should be writing in the style / form / setting in which the author I'm reading has used.
The best way for me to get back to a project (and this is a subjective solution to a problem which is personal for everyone) is to watch television, listen to music, play a DVD, put on a computer game for a while... Anything other than reading a book. When I finish watching, listening or playing, I use the stimulus to generate something that resembles useful writing. It doesn't always result in ideas, phrases or scenes that are anything near useful, but it can get me out of a rut more often than not.
I can't remember which author gave the advice, but there is a scene-adoption technique that I also tried to work with. The basic idea is to switch on a program (TV or radio) in the middle of an episode, and switch off again before the end of the episode. Your assignment would be to write a scenario that gets the characters into the scene, then conclude events after the portion you watch or listen to.
Don't give up.