I have a few tricks that I use when I don't have any workable ideas.

One strategy is simply to take a break from the keyboard. I like to run, so I go for a longer run which purges my thought process. Running also develops new thoughts and ideas. It's also a good reminder that my neighbors hate the planet and that's why they're running their sprinklers into the gutter at 11 AM on a summer day.

Another strategy is to try and add anywhere from one sentence to a couple of paragraphs to one of many unfinished drafts I have saved. I have one called "Vampire with a Foot Fetish" that has no written premise. I can't recall what my original thought was. I do think that a vampire drinking blood from the foot instead of the neck is a silly idea that can be built upon.