I know exactly what you're talking about. I have all these fics in my head and I know where I want to go with them but when it comes down to it......i just can't write anything. The best thing to do, and it has worked for me, is to just post something that says you need help with your story. You'll get a lot of good suggestions and you hope they'll help. And like everyone else says....don't force your story...it just ends up coming out wrong or sounds bad