At Nick Cave's "The Red Hand Files," the musician/poet/screenwriter responded to a fan who asked, "What do you do when the lyrics just aren't coming?" In short, Cave's answer is to wait patiently. But his full reply is quite beautiful and inspiring. From The Red Hand Files:
The idea of lyrics 'not coming' is basically a category error. What we are talking about is not a period of 'not coming' but a period of 'not arriving'. The lyrics are always coming. They are always pending. They are always on their way toward us. But often they must journey a great distance and over vast stretches of time to get there. They advance through the rugged terrains of lived experience, battling to arrive at the end of our pen. In time, they emerge, leaping free of the unknown — from memory or, more thrillingly, from the predictive part of our minds that exists on the far side of the lived moment. It has been a long and arduous journey, and our waiting much anguished[…]
Our task is to remain patient and vigilant and to not lose heart — for we are the destination.