Recovery from factory setting - lost key

Hello,



I had to put my computer through a recover to factory action. I got most of my data back, my problem is the system files I cannot recover. i used windows 7 and now when I use it is ask me to put in the product key. I dont have the product key with me, as I am working in Africa, and my key is in SA together with the Cd. How can I get windows 7 to function again after the factory setting was done.