If you have got any Modern Warfare 2 Russian key, you can use it to Install the English version of the game. But keep in mind that the word around the web is that all Russian keys will be banned. So before they do that, you can do this workaround to play English version of the game using Russian key of Modern Warfare 2.
Install English Version of Modern Warfare 2 With Russian Key
Install the English version of the Modern Warfare 2 .
Install Steam, Create a new account for this sole purpose.
Log into your steam account and make sure Its in English, add your Modern Warfare 2 CD key to activate your account. Once you have activated your account, you will see two icons “MW2 Single Player” and “MW2 Multiplayer”
Now click “Install Game” and let it load for like 10 seconds, and then go to properties of the game and select “Pause Updating” on Both.
Log out of your steam and go to “Steam/SteamApps/common” and there you would see a folder named “call of duty modern warfare 2”
Now replace your installed English Version of the game with the one in “common”. Just copy the installed English Version of Modern Warfare 2 and replace it with the one in “common” folder.
Now log into steam and Resume installing the game. Just right click on “MW2 Multiplayer” and choose “resume updating”.
Once its done, right click on “MW2 Multiplayer” and choose “Properties” then “Local Files” and finally click on “Verify Integrity of Game Cache”.
Now this will make sure that you have the latest game files if not Steam will automatically update it for you.
Done So Play!!
Now you have fully working English Version of Modern Warfare 2, if you experience problems at this stage, the only thing you should do is re log into steam and everything will be fine.