Depending on Windows 10 and higher privacy settings camera usage might be blocked due to these settings.
First verify you can see the camera in the device manger under "Imaging Devices" and that all drivers are fully installed. If you have a built in camera that you have enabled camera operation.. Typically there is a HOT key combination on your keyboard that will enable/disable camera detection, ensure this is "ON"
- Next, Left click the Windows Start icon in the lower left corner of the desktop Click “Search”