If it really existed, writer's block would be the inability to write. If we look at this idea for a moment, we begin to notice that it doesn't make much sense. Is a person with writer's block physically unable to put words on a page? If that’s really the case, it's not called "writer's block," but rather "paralysis" or "death" or "extreme drunkenness."Luc Reid's free book The Writing Engine is a great way to rev up stalled motivation to write. It's well, researched, it's short and easy to read, it's helpful and it's hilarious.
The rest of his blog is choc full of useful advice too.