What is the house battery voltage reading at the battery posts. If less than 11.7 dcv then charge the battery so it has 12.6 volts.
Is the battery switch on?
Do the 12v lights work when shore power or generator provide 110vac?
If not, then there may be one or two high amp fuses between the house battery and the inverter or converter that has failed.
My inline fuses are 300A Class T fuses.
1995 38' CC Magna #5280
C8.3L 300hp Cummins, 31,000lbs
Gillig Bus Chassis