The fill valve is not opening. If the valve is a post in the corner of the tank and the float slides up and down on it, there is a washer in the top of it that becomes stiff or plugged and does not let water in.
take a bucket full of water and use it for flushing then call a plumber for more help
Joseph Bramah invented the flushing toilet or so called at the time water closet in 1778.
Toilet tank
Each flush of a toilet uses the same amount of water.
A vacuum breaker is a device that prevents water in a toilet cistern or water tank, from syphoning back into the toilet cistern or water tank.
seal to stop water from runing into tank located between tank and bowk
Take the lid off of the back of the toilet and there will be a hole with water draing out. Above the hole there will be a plug that is attached to the flusing handle on the outside of the tank. Push the plug down into the hole (don't worry its clean water) and it should seal the hole and no more water will come out.
Install a tempering valve in water line feeding toilet. Tempering valve will mix hot and cold water together so warm water fills toilet tank which will stop condensation.
It's the Rubber seal at the bottom of your water tank, when you flush the rubber seal raises and the water flashes your toilet. Generally its black but not always.
NO.
Assuming you have a regular tank toilet with a ball float and rubber flap and that the water is turned on and the tank is filling, the most common cause of a toilet not flushing is a broken or detached chain that runs from the handle lever to te rubber flap that keeps the water in the tank.
If your water comes from a well and you have your own pump and tank. The tank may be waterlogged.
Usually not. If toilet has a mixing valve going to it so warm water fills toilet tank and toilet runs constantly, then enough warm water could leak out through toilet to possibly have an effect on water heater.