Check the fuse/circuit breaker for the outlet to see if it has been tripped or blown. Check other outlets to see if there is a GFI (Ground Fault Interrupt) outlet that is on the same circuit as the outlet used for the unit and see if it needs to be reset.
My Kenmore microwave is 16 months old and it is arcing. I called Kenmore and they said "SORRY. If you don't have insurance then we can't help you." Is the quality so bad that a consumer is forced to take out insurance now? I will never buy Kenmore products again. Now I am afraid that the stove, refrigerator and dishwasher will end up in the trash also.
In April 17, 2015, I purchased another Maytag microwave but wanted the convection oven too from Home Depot. The convection fan quit working in January 2017. I called Maytag to ask how this was covered. Maytag only has 1 year warranty on parts and labor. So basically if you don't buy an extended warranty, you are stuck with a product that quits working.