Eat something. That helps me.

Ah, damn, I hate it when that happens.

I actually find that the underlying reason is that, once I know exactly what to write, it stops being fun writing. The inspiration's gone on past, my mind starts wandering off, and there, gone.

I've had some success getting around it by starting to write when I've only got a vague idea of what I want to write, and let it develop from there.

I've also found that it plagues me when I've had a few bad nights of sleep. Getting up on a free day with no obligations after a good lie-in to recharge, it soon has the flow going again - although it remains obstinately difficult to arrange sometimes.

Sometimes, though, I just need a good dollop of motivation; try reading a chapter of a good book, watching a good film/TV series episode - do something that you know impresses you and fires your imagination, and the residual energy of that can linger enough to get some writing started (and starting's the hardest part...)

I wish I could guarantee any of these, but let's face it - if I could guarantee curing writer's block, I'd be a multi-millioniare with a series of self-help books and a lecture tour going.