I find there are some cases where my Macbook becomes completely mute, meaning each application cannot make any sound. Even while adjusting the volume, there is no sound during the operation.
One already spotted action that leads to this case is I make it sleep first, and then wake it up. Then, the computer is completely mute. I am sure there are some other cases.
The only solution is restarting the computer.
How may I fix it? Bring it to AppleCare?
Best Answer
Does this occur when you have stereo or headphones plugged into the jack, or only when using the computer's speakers?
If it is only when trying to use the built-in speakers, then probably there is some dirt or lint in your headphone jack outlet, and the computer thinks that something is plugged in there.
You can try compressed air (safe) or a paperclip (not as safe), or just go to the Genius Bar and let them sort it out.