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SafeView Shutter
Some laptops have a built-in "SafeView Shutter" to block the integrated web camera when desired.
Unfortunately, if the switch gets moved accidentally while opening, closing, or adjusting the screen tilt, you may see only a black screen and think something is wrong with the camera or with the operating system.
Troubleshooting camera issues
Check to see if the SafeView Shutter has been activated by moving the switch to its other position (#2 in the image).
If adjusting the SafeView Shutter doesn't resolve the problem, the webcam driver may need to be reinstalled, other software or drivers may need to be updated, or there may be a problem with the actual camera itself.