Sometimes it's a setting on the TV. I'm guessing you have already tried this but your TV should be set to on air and not cable. A channel search also helps sometimes. Next I would make sure the coax is actually attached. There have been instances where the coax behind the wall plate has not been attached or not attached at the antenna itself. Good luck, I know it's frustrating. I've been there myself.
Retired Fire Dept Battalion Chief
2016 Ever-Lite 232RBS
2012 F150 FX4 W/Max tow & Ecoboost
Getting old ain't for wimps!!!