Must have good 12 volts to the control circuit for the WH to operate.
If you can smell gas and hear a clicking sound at start up, it is an ignition problem which is usually the spark/sensor either being bad or misaligned.
If no gas is present, that indicates the valve is not opening for ignition which could be a lack of 12 volts to the control circuit or possibly a bad thermostat or a tripped high limit. The high limit probably requires a manual reset if it has tripped.
Resetting all plugs and connectors is always helpful and google the WH to download the service manul.