Copy the .txt or .bin files inside and paste them directly into the where the game's .exe is located.
Sometimes the game fails to initialize the sound bank because it cannot find an active audio device.
: Navigate to your main Black Ops 2 installation folder (usually Steam/steamapps/common/Call of Duty Black Ops II localization.txt : Open the file named localization.txt with Notepad. Change the Language
Black Ops 2 has a famous bug: It does not like non-English characters in your Windows username or file paths. If your Windows username is "José" or "Анна" or "あかり", the game cannot parse the Users\YourName\Documents path.