That said, I don't believe in writer's block. What it is is fear. The person writing is suddenly afraid to open the door to the story- why? Lot's of reasons- fear of failure, fear that they aren't really any good at this, fear that this is the best thing they'll ever write that it will hit the NYT list and they will suddenly be in the limelight with nothing else to say. Or fear of humiliation that people will point at laugh at them for having the audacity to be a writer. The fear of humiliation or being caught as a fraud happens even after you have several books published.
How do you stop this? Put your bum in chair and write. Give yourself permission to suck. No one but you will read the first draft. The great part about writing is that it's not done until you say it's done. A lot of people will see it before it goes public. Stories are fluid and until the book is in print it can change. So relax and give yourself permission to write. Cheers~