Get a multi-tester. I suggest you start at the batteries and work backwards.
1. At your shore power, make sure you have power. Depending on your service (20, 30 or 50 amp) you will have 120 or 220 volts. If the power is good,
2. Plug into shore power.
3. Go to your battery compartment. Make sure your house battery disconnect switch is on. Physically turn it OFF and then back on. Still no power to the batteries?
4. Many battery systems have a breaker switch on the wall where the power enters going to the batteries. See if that breaker switch is thrown. If not, trip and reset it anyway. This most often cures a problem. Still no power to batteries?
5. Go to the compartment where your coach power cord goes to your (presumably 50 amp) shore service. You should have a Transfer Switch. There should be "In" and "Out" labels on the transfer switch.
6. Before you take the cover off the Transfer Switch, ask yourself, am I an electrician (or "am I prepared to be shocked to death"). If the answer is "No," please call a mobile RV repair center if you can't start the coach.
7. If the answers to both of these questions is "yes," remove the cover of the transfer switch.
8. Still plugged into shore power, on the "Out" side you should see a large red corded wire and a large black corded wire.
9. If your Transfer Switch has no "Out" power, the switch is probably bad. This can happen from turning off the generator or unplugging shore power while an electrical load is turned on - like the A/C.
10. The Transfer Switch is ea$y enough to replace, but if you are out of your comfort zone, please refer to #6.
11. Good Luck. My guess is that you have a bad case of #4.
BTW, I'm not an electrician. This is what I observed when I watched an RV electrician fix my problem. It was #4. He said that is the most common problem.
US Army Major, Retired
'08 Monaco Diplomat SFT,
'11 Z-71 4X4 toad