Hi,
· What is the make and model of the computer?
· Was it working fine before? If so, were there any recent changes made on the computer prior to the issue?
· Do you get any error message?
Follow these methods and check if it helps:
Method 1:
If your computer is having problems with a recently installed device or other hardware, try using the Hardware and Devices troubleshooter to fix the problem.
Open the Hardware and Devices troubleshooter
**http://windows.microsoft.com/en-US/windows7/Open-the-Hardware-and-Devices-troubleshooter**
Method 2:
I would suggest you to run the Microsoft fixit tool and check if it helps:
Hardware devices are not working or are not detected in Windows
**http://support.microsoft.com/mats/hardware\_device\_problems/en-us**
Method 3:
Uninstalling and reinstalling the Logitech Webcam Software and drivers. Refer this Logitech website to download the latest drivers and software for Windows 7:
http://www.logitech.com/en-us/435/7794?selectedcrid=435&selectedcid=7794&WT.z_sp=Product&osid=&bit=