Sounds like a jam. The bottom of most disposals has a spot for an Allen key to manually turn it in the event something is blocking it. Depends on the model so I would check but most have that there as a way to clear a jam. An old-school method is to angle a broomstick handle in there, and try to spin it that way. If you don’t have a spot underneath. If this doesn’t solve the issue it may be time for a replacement.

The best place is from Whirlpool directly at whirlpool.com. But many people choose to buy them on Amazon for their liberal return policies. In the event they order the wrong one. Look at the filter itself when you remove it. Whirlpool uses an easy # system to make ordering a breeze.

It varies by machine as some brands like Miele prefer a powder while other use the tablets, I personally use the powdered tablets with the jet dry built in and they seem to work better than most.