In order to fix the issue, press the CTRL + Shift + Escape key combination, open the Task Manager and close all applications (video editing software, instant messengers, browsers) that may use your webcam. After that, go to Start, type Device Manager and open the utility. Look for the webcam driver in Universal Serial Bus controllers or Imaging devices lists, right-click on its icon and select Uninstall. After that, try uninstalling the webcam software using its uninstaller or Add or Remove Programs feature. If it doesn't work, try using Revo Uninstaller. Even if it can't remove the application normally, it will force it to uninstall by wiping out all traces of its presence from the system.