I don't usually have this problem. when you say you have writers block, does this mean you have no ideas for a book or topic?
I write fiction so I'm not sure if anything I can give helps. when the creativity has died down, I focus on my characters. I have know them like my best friends.
When I know how they respond to certain circumstances, I know how to write the dialog for that scene. I re-read my book even if its already proof-read. This allows me to enter the world I have created and take it to the next level or chapter.
I try to picture the rooms in my head and then say the words out loud in order to write them down. For me, most of this comes from my memory as most of stories are from my life in some form or fashion.
I always write down my dreams. The feelings, the words, what people look like, how the room is organized. You have to be fast on this one before it fades.
Good Luck on your next project.