Gauges Quit Working After Being Parked

The regulator probably creates a contact between one of the two terminals circled in yellow. if it is bad then there will be no voltage on the upper terminal.

One of the 2 terminals circled in red goes to the tank the other +12.

The regulator goes between the +12 and the top terminal circled in yellow.

plug the board back in and use a volt meter to determine what is what.

check to see if there is any voltage on the top terminal if there isn't then your regulator in the fuel gauge is bad. It may just need the contacts cleaned. try that first.

Good luck and be careful it is very easy to burn out the fuel sending unit. maybe you should just disconnect it at the tank to be sure.