If the circuit breakers are not the problem, I'd go next to removing the outlets to see if there is a wire that has broken or or come loose from a wire nut. This could either be at one of the outlets that doesn't work, or one of the ones that does. If you're not comfortable with working with AC circuits get help from someone who is. Make sure your trailer is unplugged from shore power and any power inverters are disconnected. If in doubt, use a circuit tester to check for current before touching any bare wires.
1946 Spartan Manor
1965 Avion C-10 Truck Camper
2005 F-350 SRW 4x4 crew cab long box