Unplug the microwave from the electrical outlet in your kitchen. Make sure there is no electricity going to the unit while you are working on it.
Remove the tray or the glass plate from the microwave oven. Clean any food that has built up on the rolling wheel.
Clean the inside of the microwave with a paper towel and the all-purpose cleaner. Make sure that you clean the groove that the rolling wheel rests in.
Put the turntable ring back into the circular groove at the bottom of the microwave.
Test the turntable after you have cleaned the inside of the microwave.
Unplug the microwave from the electrical outlet. Remove the screws holding the grill in the back of the microwave.
Pull the grill forward to remove it from the housing. Pull the bulb cover up to expose the light bulb.
Remove the old light bulb from the bulb socket and replace the light bulb with your new one.
Replace the grill and the screws holding it in place. Plug the microwave back into the wall outlet and test it.