I left the hot water taps upstairs and downstairs running and afterwards found no water at all coming through the taps , there is just a single large water tank at rooftop level attic

I left the hot water taps upstairs and downstairs running Do you live in the UK? You ran all the water. Other stories tank? Can you tell me why. How do you fill the tank? Is this a story tank or water heater? Can you give me more details? Back to you, Tom