MacBook Air loses sound capabilities

Several users have reported an issue in which the MacBook Air suddenly becomes unable to output sound. When this issue manifests, the sound icon in the menubar may disappear, and no output devices may be listed in the Sound pane of System Preferences.

Apple Discussions poster oudemia writes:

"After a day of repeated error messages after opening up a sleeping laptop (as soon as I would open it a "you must restart your computer" message would be on screen in English, French, German, and Japanese), the sound icon disappeared from the upper right corner, the prohibitory symbol would appear on screen if I tried to toggle the volume, and no audio output devices appear in the system. Zapping the PRAM worked once, but never since. "

Potential fix In some cases, this issue can be resolved by clearing audio caches. This can be easily accomplished with a tool like OnyX.

In other cases, resetting PRAM/NVRAM can resolve the issue. In order to reset PRAM/NVRAM, shut down your Mac, then start it back up while immediately holding the following keys: Command, Option, P and R. Hold the keys down until the computer restarts and you hear the startup sound for the third time.

In still other cases, this issue can only be resolved via authorized Apple repair. Contact Apple support or bring your MacBook Air to a local Apple retail store for assistance.

Feedback? http://www.macfixit.com/contact.

Resources