If you have bought a key for a particular game on steam, and want to play the game online, you will be required to install the game using that key. But in case you have bought a key of a Non English version and want to play the English version of the game, you will have to do a workaround steam to install the English version of the game using that key. Here’s how you can do that:
How to Convert DVD/Downloaded Game Files into Steam Files
Download and Install the English Version of the game, you bought the key for.
Install Steam, Create account, a new account for this specific task.
Log into your steam account and make sure its in English, add the key and you will see the game icons in the “MY Games”. Your steam account has been activated for that specific game and now you can download that game.
Start downloading the game but “pause updating” it after like 10 seconds.
Log out of your steam account, and go to “Steam/Steamapps/common/”, now in the “common” folder you will see the game folder of the game you were downloading and paused.
Copy your Installed English Version of the game or any other language to which you want to convert your game to, and paste/replace it in the “common” folder under “SteamApps”. Game folder name should be same as the one that is in the ” Steam/SteamApps/common”.
Start Steam and resume installing the game that you previously paused in Step 4.
Once the update is finished. Right click on multiplayer exe file, (There would be two executable files, one for singleplayer and other for multiplayer) and choose “Properties” then choose “Local Files” and then click on “Verify Integrity of Game Cache”.
It will upto date the game with the latest patches and all so that you can go start playing multiplayer game in your desired language version.
Note: If you experience any problems after all the this, just close the steam and log in again and it will be fine.