I'm not sure I've ever had writer's block excepting when I've been given an outline and I've had to try to write to it. Since I learned to ignore the outline, I've not had any difficulties writing. That said, the sheer physical and mental challenge of writing a book has kept me from planning another one. Maybe that is a writer's block of a sort. But if someone gave me a topic and asked me to write on it, I'd likely be very tempted if it was one I thought I had something to say about!