REFRIGERATOR HAS STOPPED WORKING , NOTHING RUNS, NO LIGHTS NOTHING

As suggested, check for AC power at the receptacle where the fridge is plugged in.
There may be a tripped GFI elsewhere in the kitchen or the circuit breaker box.
If you find one tripped and it does not stay reset, unplug the fridge and reset the GFI.
If it trips again, the defrost coil in the fridge may have developed a leak causing the GFI to continue to trip.
When starting the defrost cycle, AC is supplied to the heater coil and the water creates a path to a grounded part of the fridge which causes the GFI to trip to protect against shock.

If everything is dead the first thing you have to establish is that the unit is receiving electrical power. It is far fetched for every component to go bad at the same time!!!!!!