First off welcome to the forum. Secound, I guess I'm a little confused.
Do you not have 12 volt power or 110 volt power or both? Your lights, radio & water pump will run off of 12 volt and your fridge & water heater will run off of 12 volt & propane or 110 volt, your tv, micro, a/c will be 110. Also are you trying to run off of just a battery or are you plugged into shore power? If you are trying to run off just a battery, like others have said check to make sure the battery is good. Check to make sure connections are clean and have good contact, check the ground and like SAABDOCTOR said check the breaker. If your plugged into shore power and have no 12 volt power you could have a bad converter (had this problem ourselves on our Sprinter). If your plugged in and have no 12 volt or 110 then I would say you might have either a problem at your plug or a wire might of come loose from your power center (have ran into this also).
Once we know more specifics then we can help you better diagnose the problem.