If the lights go on ( they are 12 volt ) then the furnace should be getting power.
Check the fuse to the furnace.
If Thermostat is turned on and set to heat does the fan come on but no heat?
If so it is not lighting. If not, check wiring fuse, everything.
If fan runs and no heat after about 2 minutes, check the burner, is it getting gas? Does the pilot lighting sequence work? Check for gas on, purge the lines by running the stove. No gas at the stove, tank shut off, empty?
Read your manual, some furnaces have a switch near the fan that turns on the pilot if the fan blows it shut. It is a safety to prevent burner with no fan.
Look for junk, wasp nests, dust, cobwebs in the burner and pilot light area. Clean it with a soft brush (tooth?) and computer air blast.
After all that, ask around the neighborhood for help. Lots of RVers out there! Many will come over.
2017 SLX 195RB
2014 Jeep Grand Cherokee Overland, gas 3.7 V6
Andersen WDH hitch
Dometic Milenco Aero mirrors