Feel or look straight-up at bottom for a slot in center into which a wrench can be inserted. 9 times out of 10 slot will be for hex wrench , aka Allen Wrench. Once wrench is in place, repeatedly rock motor clockwise then counter clockwise, increasing force each time until impeller moves.

Thank you both! I will give that all a try!

Garbage disposers ship with a wrench like this. But if you don't have one, you can use an Allen wrench as described above.

before allen wrenches we used broomsticks

still works

If this is to be continued kicked around, shouldn't someone find out what key the disposal is humming in? And btw, disposals come in various horsepowers,colors and brand names.

Oh, I had a similar problem with my disposer. We hadn't used it for a while, and at some point it just started humming and wouldn't turn. It's likely not the impeller itself that's broken, but rather that it's stuck due to a buildup of dirt or rust. WD-40 doesn't always help with things like this, because everything inside gets pretty clogged. Usually, in such cases, people try turning the shaft from below (there's often an Allen key there) rather than trying to get it from above with pliers—it's safer and more effective.
And it's funny, but this is somewhat similar to situations in other industries—when a system sits idle for a long time, then you start using it, and everything gets stuck. I recently read about similar cases in business and came across Gofaizen & Scherle. The idea there is that instead of "developing and launching everything from scratch" (and running into a ton of problems), you can use an existing structure and save time on getting it up and running. With a shredder, of course, it's the opposite—you just need to get it going , but the principle is similar: either you spend a lot of time fiddling around, or you find a faster way to solve the problem.