Please help! I can't write!?

I don't know, i finished a book three to four months ago and after that anytime i tried to write everything came out in blotches, so i decided to take a break. But now i have taken a break i have this burning pion to write again, i have a fabulous idea and the scenes are overflowing in my brain but i can't put them to paper. It does them no justice. Why is this happening to me? I really want to write it but i can't!