Writer’s block is a mysterious ailment that does plague some of us. My solution has usually been to keep a writer’s journal going alongside whatever project I was working on. I’d talk myself through story lines there, make notes on things I wanted to look up, develop ideas, etc., and, when none of it was working, journal about how it wasn’t working. When I really got into bitching and moaning about the problems I was having with my writing and just went on and on about that (sparing my friends and loved ones my piteous monologues), I usually found that just the act of writing about it would lead me to a new place. You might find some helpful ideas in this question.