Hot water heater not working

That's because there is no reason to heat hot water. I myself just have a water heater.

No spiders, just rust and dust and dirt collecting where it shouldn't.

Sounds like your system is Buggy. and by Buggy I specifically mean a spider. This spider likes the smell of Propane and/or natural gas and will build its nest in the burner oriface. Cleaning same often fixes the problem you describe.

THERE ARE.. HOWEVER.. .OTHER CAUSES

One is the excess flow valve on your tank.> Does the Furnace work. Stove top work (All burners lit) if so then this valve is likely NOT your problem .. If not. then it likely IS.. To reset make yourelf a cup of coffee (May need to use and electric or campfire pot for that) turn off gas at the tank. Enjoy the coffee. SLOWLY turn the gas back on If you hear gas flowing STOP when you no longer hear it continue. till the valve is full open.

So, I fixed my hot water heater.

It is becoming a common issue with my trailer.... It needed a cleaning. After blowing out the outside area, I turned the gas on, lit the pilot, and turned it to on and the main burner lit.

So, next problem... I will just try cleaning it.

Pilot flame MUST engulf thermocouple so it heats up
Thermocouple when heated generates millivolts (12mv minimum) to hold gas control magnet OPEN so gas can flow

Dirty gas orifice...unscrew from gas control and soak in alcohol then blow dry (just blow on it ...no poking/no high air pressure)
Burner tube not 'aligned'...gas needs to flow thru center of tube/not bouncing down sidewall otherwise gas will not mix properly with air
Weak magnet.....replace gas control

Clogged orifice in main burner. Remove and soak in alcohol. Very small hole, do not use anything to clear it, except air pressure.
Burner tube clogged, remove and clean.
Bad thermal couple will not allow pilot to remain lit.

Pressure regulator can create low gas flow. Bad thermalcouple can cause no burn. What brand and model water heater?