Camera not working

The last few times I've been in a meeting I haven't been able to get my camera to work. This time it said "Camera being used by other apps. Close apps and try again", except I didn't have any other apps open. I even tried ending Norton on the task manager and turning the Safecam off/on. I've looked through all my settings, both on my computer and on Zoom, and nothing works. But when I go in my settings, I get a preview, so I know the camera is capable of working. I don't understand what's going on. If it helps I use an Acer.