Problem with mouse device

Hi,
I have windows xp pro on my pc. My ps2 optical mouse has stopped working
although light glows. When I checked out device manager, it did not show me
mouse device. While troubleshooting mouse device, I accidentally uninstalled
mouse driver. Now I cannot even troubleshoot the device from Control Panel
nor does a listing of .sys files come in my mouse driver properties. How do
I rectify this error.

Please help. I cannot work without the mouse.

Regards,

Kaustav Choudhury