Check the gas line for a valve that could be shut off. Open the heater and check the main gas valve, it will have a knob on the top that's needs to be on. If this is the model I'm thing of it will have an on off toggle switch on the right hand side of the heater about two thirds the way down the side of the cabinet on the out side. Check all these and you should be good to go.
Answers & Comments
Check the gas line for a valve that could be shut off. Open the heater and check the main gas valve, it will have a knob on the top that's needs to be on. If this is the model I'm thing of it will have an on off toggle switch on the right hand side of the heater about two thirds the way down the side of the cabinet on the out side. Check all these and you should be good to go.