No option for video

I have used Zoom many times and never had an issue. I record classes for people to watch later. Today, I went on to make a recording, and it would not do video, even though I chose video. I have not changed any of my computer settings since the last time I used it. It won't use my computer camera or an external webcam. It only gives the option for video. It will not show me in the picture. I have a Chromebook. Could you tell me what I need to do to get this to work?