Re-download the game, ensuring you choose an internal solid-state drive (preferably your ) for the installation path.
When you launch Black Ops 2 , the game engine loads a series of audio "banks," which are packaged files containing all the sounds for a specific part of the game: dialogue, gunfire, ambient noise, etc. The cmn_root.english file is a critical common audio bank for the English language version of the game. If the engine cannot find, read, or properly load this file, it halts the initialization process with the error you see. black ops 2 sound bank failed to load cmnrootenglish link
The "sound bank failed to load cmnrootenglish link" error is annoying, but it is fixable. In most cases, Windows is simply struggling with how deep the file is buried in your hard drive. By moving the game to a root directory or a shorter file path, you can usually get back into the multiplayer lobby or Zombies map in minutes. Re-download the game, ensuring you choose an internal
Switch the language to something else (e.g., French or Spanish). If the engine cannot find, read, or properly