First guess would be a breaker is tripped. Second is you inverter may be going out and needs to be replaced. If those don't work you may need to call a good tech.

You didn't mention if you are on shore power, generator or batteries. If on shore power i would look at 2 items, a possible tripped GFI breaker or the interrupt realy the stops some outlets from working when the ignition is on. Another possible is the circuit breaker on your inverter. 

On generator or batteries there are some outlets that are not active. Normally it is not a whole region, but rather selective outlets like one side of a bed works but the other does not.