How can i install a4 tech pk 635 web cam

You can download the driver direct from A4tech's website. Here's the link for your model:
http://www.a4tech.com/download%20driver.asp?cmodnum=PK-635

1st You download Webcam Driver.
can i install a4 tech
After this install the Webcam driver in the system.
Installation of Webcam Driver
Go to the control panel
Click on the System Icon
Click on the Hardware Tab
Click on the Device Manager s
Select the Unknown Device or printer device where yellow Question Marks sign on it.
Right click on it and uninstall it.
After this go to the top of the device manager and click on scan for hardware changes.
Driver installation Wizard start.
Brows Your Driver from the Hard Disk and click on next.
Driver will be install.

A4tech Viewcam Pro Pk 835 Webcam Driver Download
Driver FileName ( s ) :A4_IM_Magician.rar Feature :For MJ & E Series Apply for Model ( s ) : PK-760E ' PK-336E ' PK-335E ' PK-333E ' pk-635E ' PK-836MJ ' PK-835MJ ' PK-800MJ '
PK-750MJ' PK-730MJ ' PK-720MJ ' PK-710MJ ' PK-600MJ ' PK-200MJ ' PK-130MJ ' PK-30MJ
' PK-8MJ ' PK-5MJ
System Requirements : Windows 2000/XP/Vista/Win 7,MAC10.4.8 Version :V1.0 Update :2010-11-22 Download Link: http://hotfile.com/dl/97484719/c131bdf/A4_IM_Magician.rar.html
Notes: * All PC Drivers are in Zip format . Therfore , if you do not have Zip software yet
, please download & install WinZip before installing the device driver . Instruction on How to download and install the driver properly : 1 ) Press Download button to download the desired driver . 2 ) Save it somewhere where you will remember after download . We recommend that
you save it on your desktop , so it will be easy to find . 3 ) After successfully downloading the driver , do not open the driver file until
you make sure the following has completed : ***REMOVE / UNINSTALL any original
mouse driver from the PC . ( If you forgot to do this part , your driver may not be
able to install correctly and successfully later ) 4 ) After the original mouse driver has been removed , open the downloaded file . 5 ) Follow the on-screen instructions . 6 ) When it's successfully installed , please restart your computer . 7 ) After you have restarted the computer , plug the webcam into your computer and
it will automatically recognize the new hardware.

You'll need to download the driver from the manufacturer's website, or use a driver finder program to locate the right driver for it.