If you you have a prepay (Quantum Meter ) one that you put a credit card size token in that you get charged up at your local shops. Then they have a tamper proof device in them that are quite sensative. Is it possible that you or someone inyour family has accidently knocked it or maybe a pet has knocked it. that is all it will take to Shut off the gas supply. If So only your gas supplier can reset it with our pass card key. It wont cost you anything.. Or aswell as the above answers has it run out of credit ??? There is a button to press that will give you a small emergancy supply. till you get your card charged again.