The temperature gauge has no electrical connection at all. What you call a sensor is a fluid filled bulb that reacts to changes in temperature. If that bulb or the line leading to the gauge has been compromised the gas would have leaked out and it won't work. There can be other reasons for it not to work too but it will require heat to show an increase.

You will really be better off using the search function for the gas gauge problem. There is lots of trouble shooting advice that should be easy to find.

Chuck