Most hot water heaters' cycle pumps just plug into a 110V outlet. But some are hard-wired electrically, and wire nuts or connections may become loose. Before you check that the wires are all secure, go check and make sure the circuit breaker for the water heater wasn't tripped. If it wasn't tripped off (which is usually the problem) shut off the breaker. Go back to the electrical connection on the water heater and make sure no wire nuts are loose and check that no wires have become loose from under the screws that held them down before.
If the water heater is cycling and turning on but the water isn't hot, then there is something wrong with the propane connection or heating burner. First check that there is propane in the propane tank that is located outside of your home. Check that the connection on the tank outside is good and securely fastened to the water heater inside. Open the water boiler compartment door. There should be a pilot light flame in the burner (a propane flame should have a bluish-green flame). If there isn't any flame, shut off the gas for a few minutes to let any gas in the chamber disperse and not cause an explosion when you light it. Turn on the gas and try to manually light it. If it doesn't light, turn off the gas again. You will need a professional from the water heater manufacturer to install a new pilot control valve and thermocouple.
Particles in the Water
If the hot water takes a long time to come back, if there are particles in the water, or if the water if discolored, this is a sign of a buildup of sediments in the hot water heater tank. Shut off the water source and unscrew the base water connection. Drain the tank all the way and then flush it with clean water until you don't see sediment coming from the tank hole anymore.
If the water from your water heater begins to smell, purchase a small dose of drinking water-safe chlorine and add it right into the water heater tank.