I have a wall switch for overhead lights and it suddenly stopped working. If I use a circuit tester on the two exposed black wires, the little bulb on the tester lights up, but if I touch the two black wires together, the lights do not come on. I checked the bulbs and they are fine and I check the connections to the overhead lights and everything looks secure. Any suggestions?

Have you tested what voltage you are getting at the wires both at the swith and at the light fixture

Also while they Look secuire have you actually checked them.

You could turn power off, jump connections at switch, and restore power. If it lights, it is a bad switch.

How many wires at the switch? How are you wired, BX, conduit, or Romex?

Two sets of Romex wires; one from the power source, the other from the fixture.

At switch box, Be sure the 2 whites are intact, jump switch, then test.
At the switch box, you should have voltage between the whites and one of the blacks.
If not go back to panel, and verify breakers all have voltage.