Video doesn't work during the zoom meeting

I have a problem. During the zoom meeting when i opened the video, it gave me a black screen. And when i opened the video setting also gave me a black screen. I tried to switch to mobile zoom to open the camera, and i had the same problem. When i open camera app of my laptop it's working. Before and after the zoom meeting, when open video setting in zoom app, i found it's working with me. I don't know why it is not working during the zoom meeting, and it's important to open camera because it is online course, and it's very important to open camera during season