I was told, "to keep from getting writers block, just write, write something, anything, just write and keep on writing. eventually your penmanship will keep pace with your thoughts and that will occur less. and less".
take a break. watch a movie of the same genre you're writing. eat some food that you like, even if it's junkfood. watch Transformers. fall in love with the transformers. um, go outside and take a walk.
Ideally when your a writer you should keep a journal with you everywhere and write short journal entries of thoughts, ideas and encounters you have throughout your day its called free writing. If you have a bunch of journal entries then when you get writers block all you have to do is look through your jounral and pick a idea or encounter that you wrote about and elaborate off of it.Otherwise dont think too hard on a work just let your writing flow out of you like a river. Ride the river and let it take you.