If your computer doesn't see your webcam at all, the issue is physical or driver-related. For USB webcams: unplug and replug the cable, try a different USB port (avoid hubs), and test with a different cable if possible. On Windows, open Device Manager > Cameras or Imaging devices and look for your webcam — if it has a yellow warning, right-click and choose Update driver or Uninstall device then restart. For built-in laptop cameras, restart the computer first. Some laptops have a physical privacy shutter or a keyboard shortcut to disable the camera — check for a camera icon on your function keys. On Mac, open Terminal and run "sudo killall VDCAssistant" to reset the camera driver. If the webcam works on another computer, the issue is software on yours. As a last resort, check BIOS/UEFI settings where some manufacturers allow disabling the internal camera.