I had received my Laptop with Factory Installed Windows XP professional. Due
to corruption of certain programs I had sent for correction and the support
person installed  adifferent copy of Windows XP with a different or
mallicious installation. I don't have  a copy of the original software and
neither is this new copy accepting my original license key.

What should I do to get the original software copy and install it?

This is a serious issue as my system has stopped getting updates.