Take a piece of writing that you’re currently working on and set it next to you (bring up the file on your computer, whatever). Preferably use a short story for this, or a single chapter of a novel or novella. First, write a “summary” of the story in the form of no more than ten short, declarative statements, one to a line. For instance,
Jack finds his father murdered in his childhood home.
Jack searches for the killer.
Jack figures out who the killer is.
Jack catches up with the killer.
Jack takes revenge.
Next, using each declarative sentence in turn as a “prompt” in its own right, free-write for five to ten minutes about each prompt. Don’t worry about what to write or what you’ve already written or planned out for the piece; just see what pops out as you go.
Sometimes looking at the structure of your writing in a new and different way can help you to come up with new ideas.