I've lost my serial key

Sir, i had purchased NFS shift 2 unleashed limited edition original CD for PC platform. Now i want to install it on my pc once again but the problem is i have lost the user manual containing the serial key for the game. Is there anyway i can get it back ? please i hope you can help me out i dont want Rs.999 to go to waste.

P.S - In the product selection i couldn't find Nfs shift 2 unleashed so i checked the run instead