The trick — and it’s imperfect and can take a while, but — is simply to write something else. Don’t let your hands go cold. Don’t let yourself stop thinking. Shift to something different.

[…]

It’s about letting your backbrain chew on the problems while your frontbrain is amused by the new and shiny things.

[…]

Write something else. Anything else. Either you’ll solve the problem in the background, or get the taste back for what you’re stuck on — or, guess what, maybe that whole thing was dead and you were just shoving electrodes up it to make it twitch in an awful semblance of life the whole time.