Writer's block gets me stuck often enough... and right in the middle of a manuscript too! It drives me absolutely crazy and sometimes, it seems as if there's nothing I can do about it. But after facing this problem time and again, I've begun to notice a trend.
Every time I get writer's block, I pick up a side story that has been sitting on my flash drive forgotten. After working on that side story for a week or so, something always happens to get me back on the original story, newly inspired.
Sometimes the inspiration comes from a scene in that side story, or something that happened during my day. Most often, the inpsiration hits me when I'm doing mundane things... like watering the lawn, or cleaning the bathroom, or picking up after the dogs.
Those little mundane jobs get the creative parts of my head going like nothing else. Entire scenes will play through my mind till I just can't wait to get back to the computer to write it all down. The characters speak to me during those times, exposing the things that make them tick.
Don't let writer's block get you down. Let "the boys/girls in the basement" do some work, as James Scott Bell says.