Do you see a red error message that looks like the below image?
If yes, Shutdown and restart your computer. This will fix 99.9% of all issues.
The reason you are seeing this error:
Have you used Zoom, Skype, or any other video app recently? Some poorly written applications on a computer can restrict access to the camera, so make sure to close any application that might already have that access, for example, Skype / Zoom, video editing software, etc. When these apps restrict access to your mic and camera, you need to restart your device to fix the issue.
Need more help? Contact Us (bottom right).