camera on Macbook Pro doesn't work

I have been using Zoom almost daily for meeting with students. Today, my camera no longer works and I am not given the choice of connecting with video. I simply get audio option and a black screen instead of appearing in my meeting in person. Audio works fine but no camera.

Tried Photo booth. Same result, black screen. When I go to Photo booth the green light comes on for a couple seconds but then goes off. No other sign of life for the camera.

Went through reboot and an attempt at resetting SMC. When I go to System Preferences/Security & Privacy/Privacy, the camera is not listed in the left hand menu as the directions describe.

Advice?