Have your webcam plugged in then in Windows
Device Manager (use search to find this or On the desktop or in the Start menu, right-click on My Computer and select Properties. In the System Properties window, click the Hardware tab. On the Hardware tab, click the Device Managerbutton ) Then click on the > icon to drop down the menu next to Universal Serial Bus Controller. You should see the Logitech webcam there. Finally right click on it and uninstall driver>
After that unplug the webcam, restart your computer and plug the webcam back in. Windows should download the correct drivers again. If not youll need to download them from the link I provided, (if you are scared to clcik the link, then go to Logitech support on their website and you can find them.)