If I have the luxury of time, I take a complete break from writing. Even from writing in my head. For me, there's a fair amount of performance anxiety involved. So, if I can get some distance and stop stressing, things usually just start happening again. A lot of it is faith. I *know* it will come back. I just have to be patient and nonjudgmental with my head.

If I don't have the luxury of time, a really moving deep plotty movie often gets the juices flowing. I also have particular pieces of music that can trigger certain "themes" for me. Sometimes I just sit down and start writing and tell myself not to stop, and maybe after about five pages of crap, something good happens. I often experience writer's block like a blocked pore to my psyche. Squeeze out the metaphorical blackhead by "writing past it" and things improve.

Hope that helps. I sympathize.