Sounds like the battery disconnect is tripped or open. The batteries are on one side while the coach loads AND the converter are on the other. Try this if you still don't have 12VDC. With the generator off and the coach dead hit the AUX Start and see if you get 12VDC back. The AUX Start works in both directions. House to chassis or chassis to house. If the lights come back on then there's a problem with the house battery solenoid.
Also Winnebago has complete electrical power wiring diagrams on line available
HERE.
