Lost my Cd-Key

Today i went and got the game but the problem is my little brother took the case and everything else. now i cant register for online play. so is there a way to retrieve the cd key? i already tried finding it in the registry editor but had no luck. any suggestions on getting the cd-key?

did you actually register the cd key and install the game?

do you mean register as in online? or registry editor? and no i didn't online.

and where's the case nao?