Copy the extracted localization.txt file and paste it directly into the root folder, overwriting the old one.
If it says "russian" or "polish," the game will ignore your new English files and attempt to load the missing regional data. Where to Find the Files call of duty modern warfare 3 2011 english language pack
Copy the extracted localized_english_iwXX.iwd files. Paste them directly into the main folder: ...\Call of Duty Modern Warfare 3\main\ . Tweaking Configuration Files (The Final Step) Copy the extracted localization