To use the webcam in Windows System, you will need to turn on some permissions in Camera Settings.
Open the Settings app by pressing the Windows + I shortcut key, or clicking the Settings icon from the Start Menu in Windows system.
From the settings windows, click on privacy settings.
In Allow access to the camera on this device, select Change and make sure Camera access for this device is turned on.
After that please enable webcam & microphone in browser , if there is any issue please visit the link
Move your cursor all the way to the bottom right corner of windows to reveal the side Charms bar.
Select "Start" from the options there to go to the Start menu.
Click on the "Camera" app in the purple box on the right of the Start menu
Click "Allow" when the permission screen appears to allow the app to access your camera and microphone
In the era of privacy and security. Some laptop keyboards have keys to enable and disable your webcam, Some built-in and external webcarns have a slider or lid that can black the image out Not only that, but totally disconnect the webcam from the laptop or computer as well. our first advice is to check your keyboards and make sure none of them is disabling the webcam. and check the webcam itself to make sure the lid / slider is open if existing,
Check and fix your webcam driver in Device manager
All of your connected devices should appear in your Device manager List Look to see if your webcam appears there and fix it:
Right-click on your computer icon and then choose Manage.
From the left pane, go to this path: Computer Management (Local) > System Tools > Device Manager.
Expand your user > Imaging devices. In this sub-list, you will be able to see all the webcams connected to your computer.
If you can see a downwards arrow on your webcam icon, this means the webcam is disabled. In order to enable it, simply right-click on your webcam and choose Enable.
If your camera is already enabled, right-click on it and then choose Update Driver Software…
Click Search automatically for updated driver software and wait for the process to be done. If there is a better driver available, your computer will download and install it. Otherwise, it will tell you that the best driver is already installed.
If you've enabled your webcam or updated the driver, try and reboot your computer to see if it works.
If you're still encountering the same issue, it's time to roll back your driver, this will restore the version before the existing one, only if it has been updated before. Right-click on your webcam and then choose Properties.
In the Driver tab, click the Roll Back Driver button.
You will be asked for confirmation before rolling back the driver. Click Yes in order to give it the permission.
After rolling back your driver, you will be asked to reboot your computer. Make sure to save your open files, and then click Yes.
After rebooting, give it another shot to see if the webcam is functioning.