I'm not sure, because as far as I remember I haven't, at least, not a full-blown-can't-write-squat. That isn't to say I haven't had writer's block before. I just don't remember. My mind is like a sponge that way. When it gets full of water stuff drips out the bottom.
The best cure for writer's block is, of course, to write. So I'm going to be taking down notes today at work and really try to put myself into that opening that I want. And then, tonight, I'm going to write. Even if it's crappy. Even if I'm sure it'll never see the light of day. And I'll keep going.
I know I've got something going on because the last few things I've tried to write were short stories and I didn't finish them. The idea of working on novels ... I put them off. I make excuses. But I know intellectually that I've written more words into novels than anything and it's novels that keep me writing, so novels should get me writing again.
In the meantime I'll try to write some articles and maybe have another go at short stories or whatever. Whatever keeps me occupied when I put my butt in the chair. The only rule is that if I start a short story or an article, I have to finish it. All the way to the end.