Some laptops and portable devices have a physical switch or button that turns the camera on or off. When it's turned off, your device may not recognize that there's a camera installed, or it may cause your camera to show an image of a camera with a slash through it. If your laptop has a switch or button, make sure it's in the on position before using your camera.
Those switches or buttons may not be easy to find, so make sure you check all possible places. For example, it could be:
Camera button:
Camera switch:
Camera shutter slider:
