This is usually due to a version mismatch between the language pack and the game executable. Ensure you are using files compatible with the latest version of the game.

Replace the existing localization.txt in the main folder with the English version.

Go to your Steam installation path (usually C:\Program Files (x86)\Steam\steamapps\common\Call of Duty Black Ops II ).

Ensure your localization.txt is properly formatted. If it says "russian" or "polish" inside the text file, change it to "english". Is it Safe to Use Language Packs?

If the "Language" tab is missing or English isn't listed, your version is region-locked, and you will need to use Method 2. Method 2: Manual Installation (For Region-Locked Versions)