Q: how do I turn off optical digital-out port?

Just blew (really hard) in my headphone jack and got my sound back! 'Optical out' turned into 'internal speakers' after blowing. No red light anymore. However silly it may seem, only this solution (on the many that are circulating) has worked with my macbook.

My problem started with Yosemite.  Although that could have been a coincidence.  I was also plugging in a headset formerly used with my Air, which tends to be more robust than my Pro.  Plugging and replugging, and simply blowing air into the jack, are not reverting its behavior to normal.

What and where is AUDIO MIDI?

I got the same problem after installing Security Update 2014-005 on my 15" mid-2012 Macbook Pro. My internal speakers just magically disappeared from sound devices in System Preferencies-Sound.

I made it works. What iI did was hit play on my music in iTunes with my headphones plugged in, opened the Sound preferences pane in System Preferences, then I unplugged headphones and plugged them back in, then unplugged them again, until eventually sound came back on the internal speakers.

It wasn't Yosemite.  It was, as others have pointed out, a flaky digital-out port.  Something caused it to unlock, the red light to go out.  Now I'm not using that port for anything, not with the cheap Sony headphones I use with my smartphone.  I'll stick to high-end plug-ins -- or better, my USB headset.  I'm playing it safe!

Thanks body you save me some money , your advice was accurate.I appreciate.

Blew in the headphone jack worked!  I was pretty skeptical at first.  Didn't even need a restart.

The "blowing" trick is not working for me.  How do I find the Audio Midi setup?

Thank you thank you soo much.

this saved my life.

This worked 100% no toothpick no nothing..

https://www.youtube.com/watch?v=u58JlKrTRqE

Internal Speakers not available in Audio Output

I tried two days all solution points listed but often also before.

I did not realized that it could be something else than settings; that it could be hardware.

I saw in sound setting that the Digital Out/Optical digital-out port was selected when headphone was unplugged.

I tried with tooth pick, ... Not worked.

I bought a Dry Air Spray. Sprayed inside and immediately Built-in speakers came back in sound setting. So, just a dust issue.

Man I could hug you!

thanks so much for your post back in 2012 - it continues to do good in the world!

I tried something a bit nuts, but it worked out!!!

I have this intradental brush at home that I never used. So after reading about toothpicks, headphone jacks and the sort... I decided to insert the intradental brush (a bit like this one: http://www.nakano-ds.com/image5.gif  )  a few times in the headphone jack (with the computer turned off of course), and it seemed to do the trick. My speakers are working again!

Shortly after upgrading to OS X El Capitan from Yosemite the internal speakers 'disappeared' leaving 'Optical Digital Output' only. My headphones still worked and when restarting the internal speakers made the usual restarting sound(?) but no sign of the Internal Speakers. I ran iTunes and played a song with headphones plugged in and playing then unplugged the headphones without stopping the song and Voilà! the internal speakers 're-appeared' and sound played through the internal speakers. Restarted and the internal speakers still operating. Thanks sergyfrombellevue 8-)