So, the family complained the water is COLD, no hot water. The first thing I checked is the pilot light of the water heater, sure enough, it’s out. I replaced the water heater thermocouple a few years ago. Removed the cover and tried to do the pilot lighting procedure on the water heater sticker, no light with sparks of ignition. Went to home depot and get one. Put it in and nothing. So, before we go out to get the new thermocouple, make sure the pilot lighted first, hold it for 1 minute, if it doesn’t keep lighting after releasing the gas push-down (red) switch, the it’s the thermocouple, but this time, the pilot didn’t even light up.
Somewhere on the internet, people say the pilot gas tube (small gas line to the pilot) blocked, so I blew it, it was blocked. Used a small wire and poke through, until I could blow it through. It fixed the pilot from NOT lighting up. I also use actual fire through a long stick to make sure the spark from ignition is NOT to strong to light the pilot.
Since I bought the thermocouple, I replaced it anyway.