Please visit the manufacturer's website to download the drivers for your device. You can use google to find the manufacturer's website if you do not know it. In the support section download the drivers for your specific make and model of the device for your version of Windows.
Note: If the manufacturer only lists drivers for Windows XP and not for Windows Vista or Windows 7, that means the device is unsupported or incompatible with the unlisted operating systems.
My name is Kunal and I work for the Social Media and Community Team at Dell. You can install webcam drivers from www.smartsource.dell.com , in this website you need to create user account and once you log in you can see the webcam driver in the list. Follow the instructions to install drivers and you will be able to use webcam on your laptop.
Hope that would resolve the issue and you need not have to spent a $.