Diagnosis
Total power failure. The most common cause is a tripped thermal fuse inside the unit or a loose power cord connection at the wall.
How to Fix It
Check your kitchen circuit breaker or GFCI outlet first. Unplug the microwave from the wall, wait 60 seconds, then plug it firmly into a different, known-working outlet. Listen for a faint hum or click when you plug it in.
If That Didn't Work
If other outlets work, the microwave's internal thermal fuse may have blown due to overheating. This requires disassembly to check and replace—not a user-serviceable part.
Heads Up
Don't repeatedly plug and unplug it trying to get a response. If it's completely dead on a good outlet, it needs professional diagnosis; attempting to bypass fuses is a fire hazard.