If I've writer's block, I occasionally just create random words, and hopefully some concept will come from that. Take a pencil, or an empty Word document and just begin typing or composing words. Some thing is bound to hit you eventually. I used to just do these exercises where I did nothing but write random sentences with out using punctuation. This helped my brain juices to flow, and it allowed me to create some short poems and short, short stories. Sometimes that rare moment when two words fit together perfectly to give you a great concept for a story occurs, and who knows? Maybe those two words can launch a series of books, or a series of plays, or the great American novel.