Diagnosis
The turntable motor has failed or the drive coupler is damaged. Food rotates via a motor under the cavity.
How to Fix It
Remove the glass tray and roller ring. Inspect the drive coupler on the floor of the microwave. If cracked or worn, replace it. If intact, test the turntable motor for power and continuity.
If That Didn't Work
Ensure the glass tray is properly seated on the roller ring. Misalignment can prevent rotation.
Heads Up
Do not operate the microwave without the turntable components. It can cause arcing and damage.