Relax, don't panic. It was working a few hours ago? Check for a loose cable connection. Also, the connector header on the Squawk and Talk often loosens up over time. It may need to be re soldered.
Go online and order a manual. You'll need it to maintain your game. In the meanwhile you can download it here. https://www.ipdb.org/files/762/Bally_1981_Eight_Ball_Deluxe_English_Manual_includes_paginated_schematics.pdf