I can't figure out how to get cold water. It used to be separate - ,but now only hot comes out. Even in the toilet! And it's scalding! I've tried flipping switches and lowering the temperature on the tank (there are two thermostats). The tank is 3 years old and no one has ever touched it. Help! I have to go to my gym to shower or I'll burn myself.

Check your supply lines.

Did you have any plumbing work done at your house in recent days ? If positive, what type of work ?