As your webcam doesn't work, go to My Computer>right click>Properties>Hardware tab>Device Manager>Imaging Devices>right click on your Trust webcam>Properties.
Ensure that the device is working properly and that it is Enabled in the drop down menu.
If not you may have to reinstall the drivers, which can be obtained from the Trust website.
However, you could first try Uninstalling the webcam from its Properties in Device Manager and rebooting - Windows should Find New Hardware and reinstall the drivers.
By the way if you use the webcam plus other imaging devices such as a scanner, you will have to list the webcam as the Default device for use, for instance, with Skype.