I bought a retail version of half-life with no CD key, before I reinstalled windows I got the CD key from the Steam version of the game that I had bought, and that worked to activate the retail version. I found the key somewhere in the registry, now I have reset my PC, I don't know where I found it but have looked everywhere I can imagine it being but I can't find it.
I think this may be because I got the game from a bundle, perhaps this gives you a CD Key for all of the games in the bundle and if you use a CD Key, it saves it in the registry. Or maybe a key is put in the registry of all the games you buy but they get removed after reinstalling Windows.
Is there any way of activating my retail version of Half-Life without buying a key?