If your coach is 50 amp you could have lost one of the two hot lines. Cycle the main breaker in the coach and on the shore power pedestal.
Since the mains are usually mechanically connected inspect the breakers carefully to ensure both are all the way on. I had mine trip once but it didn't pull both breakers open. Everything looked fine at a glance but a close look I could see one of the two breakers was not fully closed.
Coach builders will split the power load between the two AC lines to balance the electrical load. One line probably has the cooling side of your climate control, microwave and AC to DC convertor, outlets. The other could be your water heater, electrical air heating, washer/dryer and such.