Sounds like your Battery Disconnect switch is off - or the relay that makes it work has failed.
When using shore power or generator, your converter/charger is supplying 12v for lights and such, but without them it relies on the batteries. Your slides and jacks have their own direct connect to the batteries, but everything else passes through the Battery Disconnect relay.
Do you know where your battery disconnect switch is? What year/make/mode coach is it?
2004 American Tradition; 2014 Buick LaCRosse
Homebase in the Ocala Nat'l Forest near Ocala, FL