My 12 lights and other appliances do not work from battery

Be sure the reverse polarity fuses (Two or three 30 or 40 amp fuses) on the converter are not blown. Find and check the inline resetable 12 volt fuse within 6 feet of the battery. Be sure the battery disconnect switch is in the use position. Find and check the battery disconect relay. Be sure to check the GFI reset on the inverter.

"Lights and other appliances" is not enough information. We need to know ALL that don't work.

Thanks for the class 101 on how to use a test light. I'm 76 years old and have been fixing things my whole life. The use/store switch was my first guess but I would have thought this would interrupt 12 volt power to the 12 v panel on fuse block. but there is power there when not plugged in just not getting out to the lights.

I guess I would be sexist if I said the reply from the RVlady is about what I would expect from someone who has never fixed anything in there life.

I do have a converter not a inverter , sorry about the improper nomenclature.
The use/store switch only has small wires attached to it so I'm assuming it controls a solenoid , most likely one of those that are located close to the coach batteries, which are located under the hood in front of the engines.
All HELP is appreciated. I guess I don't consider recommending I take it to a shop to get repaired help.

Some Inverters are also converters

#1 Suggestion is the "Salesman's Switch" May be marked AUX or may be marked Use/Store

#2 is a main fuse or circuit breaker.

How to find problem: Tools needed: A test light. this is a device that you get at Auto stuff places (Auto zone, Discount Auto Napa Auto dept at super store)

Looks like an ice pick with a light in the handle and a wire

Clip wire to unpainted metal part and touch positive battery terminal. Bright good. all else bad

Now move on out the positive lead till you find a terminal. Touch Bright good

If you have to move the ground clip re-test last good point to make sure you have a good ground

Problem exists between bright and dark

Not the question you asked, but something to know
You said inverter
An inverter uses the batteries and makes 120vac
A Converter uses 120vac shore power or generator power and supplies 14vdc needed to charge the house/camper batteries and power the lights , water pump, appliance n controls etc..
A combo inverter-charger does both
I'm an not familiar with your RV, but think it probably has a converter, not a combo unit
A brand name and model number will let us clarify what you have
It sounds like the house batteries are Not being connected via the disconnect switch or are possibly dead
Can you get voltage reading on the charged batteries while on shore power, it should be above 13v while charging, also get a reading in the converter, from any of the fuses, or from any red and black wires
You may have more batteries, or the charge solenoid might not be working correctly, or there could be a blown fuse in that circuit

Coach batteries under hood? May be, but my coach batteries were always somewhere else in the coach, compartments or under steps into coach. Under hood were engine batteries. My battery disconnect was always for the coach batteries.

If me, I would look for a mobile rv tech or if unit is driveable, do you have a dealer nearby?

Battery switch off or "salesman's switch" flipped?
12V circuit breakfailed/tripped?

The batteries are fully charged. They start the generator fine. Everything worked fine when generator was running. Previous was inexperienced with RV's and thought the batteries were only for starting the gen set. He didn't know the switch I mentioned was there.

The batteries could well be depleted. Test for voltage. Did the 12 volt lights etc. work on your pre-purchase walk through?