Is it set to be off via the control panel?
You can download Kitchenaid / Whirlpool owner's manuals, installation manuals, and parts lists here
The turntable system consists of the motor, the coupler, the turntable support with rollers, and the tray.
You can see and hear a video
of how a turntable motor should sound when you rotate it by hand.
If yours is not set to be off via the control panel, and it won't rotate or it sounds like it's grinding, etc., you may have a bad motor or plastic coupler.
You can find helpful exploded view diagrams and order parts by entering your full model number from the tag here