Webcam issue

i installed a4tech pk-635k in windows 7 then i seen black screen on the cam so what im gonna do to make things clear? please help...... thanks ang God bless U all

Taling, first of, welcome to the Forums.

Now, could you describe your problem in more detail. What do you mean by seeing black screen on the cam? Do you mean that you can't use Windows anymore, or that your cam does not work in some application that you have installed along with the device?