Quite often, I see similar posts and the answer lies in GFI switches being triggered in odd places. Make sure you haven't popped a GFI switch in the bath or outside areas, or anywhere else you might have a GFI. If you have one that triggered, it may shut down the whole circuit it's connected to, including the microwave.
Then, if that doesn't fix it, see if you can access the plug that the micro is plugged into. You may actually have to remove the microwave. Then try another electrical item such as a fan or light in the outlet. Also try plugging the microwave into an outlet you know is good.
This will help you determine if the microwave or the circuit is the issue.
2016 Ford F350 Turbo Diesel SRW 4x4
2017 Grand Design Reflection 297RSTS
2013 Ford F350 Turbo Diesel SRW 4x4 (Destroyed by fire - 8/29/16)
2014 Grand Design Reflection 337RLS (Destroyed by fire - 8/29/16)