Identify your current regional files, which typically follow a standard prefix convention (e.g., localized_ru_iw07.iwd for Russian or localized_zh_iw07.iwd for Chinese).
Copy your zone and main folders to a safe location.
When Call of Duty: Infinite Warfare launched, Activision implemented strict regional stock keeping units (SKUs). If you purchased your copy from a foreign marketplace to save money or live abroad in a non-English speaking territory, your platform might prevent you from changing the language via standard options.
If your Steam version is strictly region-locked (such as RU/PL variants), the native drop-down menu will not include English. You must manually swap out the localization archives. Call of Duty®: Infinite Warfare | Campaign
Consoles often lock the game to the region of the digital store or physical disc.
This method forces Steam to download the English depot using console commands.