Microwave not working. We have an "over the range" Whirlpool Roper microwave. All of a sudden,

Question

We have an "over the range" Whirlpool Roper microwave. All of a sudden, the microwave stopped working, i.e., it does not heat up at all inside. All of the other features seem to be working....the timer, the interior lights, sound, etc. But, all food items are stone cold when you take them out of the oven. Do you have any idea what the problem may be?Thanks for your advice!