First of all I must say, I don't possess any magic keygen or anyway to get these all for free. If you bought the game, then you should have a key, right? Exactly.
This is meant for those poor souls who purchased and downloaded Call of Duty 4: Modern Warfare from steam directly, and do not have keys.
Now, without further a due, let's get this started.
Head on over to your start menu. From there open up run.
If you don't see run, then simply click, "All programs", and go to,"Accessories", and open run.
Start>Run / Start>All Programs> Accessories>Run
Whilst you are still in run, clear out any old commands in there, and type in:
...and press enter. Allow it to be opened, of course!
Now when you are in regedit.exe, or shall we call it your, "Registry Editor", double click the HKEY_LOCAL_MACHINE folder. In here open up the SOFTWARE folder, and then the ACTIVISION folder. Finally, open the Call of duty 4 folder.
regedit.exe>HKEY_LOCAL_MACHINE>SOFTWARE>ACTIVISION >Call of duty 4
BOOM! now you see a bunch of different files! Which one to choose? The answer:
this is your file which contains your key, obviously. It is indeed a REG_SZ type registration, and the numbers under the data column resemble your key. If you double click it, then you should be able to copy it. Save it to a different document, just incase .
Note: This is a 20-digit number. When you enter it in-game, it will be divided in to 5 parts, each containing 4 numbers. Confused? Don't be. Just type it in.
Call of duty 4>codkey> YOUR KEY IS HERE!
And there you go!
I apologize if this has already been posted in another thread... I'm just trying to help /. If this doesn't work for you then... contact steam support and ask for a new key