The error "sound bank failed to load cmnrootenglish link" typically occurs when the game is unable to access or load the necessary sound files, specifically those related to the English language pack (cmnrootenglish). Several factors could contribute to this issue:
The game's properties might be set to a language (like Spanish or French) that wasn't fully downloaded, causing the "English" sound bank to be missing. black ops 2 sound bank failed to load cmnrootenglish link