What if a young lawyer found out the firm he worked for turned out to be run by the mob?
What if a young orphan boy found out he was a wizard?
What if someone heard a knock at their door, and their ordinary simple life was going to be turned upside-down by a great adventure?
What if a school teacher found a portal to the year 1958, and set out to stop the assassination of JFK?
What if a teenage girl fell in love with a guy who turned out to be a vampire?
What if a farmboy found himself thrust into an epic battle of good vs. evil?
I don't think I have to tell you what novels/movies these ideas point to, but you get the idea. What if questions are a great way of generating ideas for stories.
Here's my favorite: ever heard of the phrase from a movie trailer that starts with "in a world" - that's the creation of the late Don LaFontaine. I use his voice to work through many of my what if's.
Try it. See if it works for you.