My volume icon is greyed out and I cannot get volume

pretty sure it just kills the coreaudio process. 'sudo' runs the command as root user, because processes like dock and coreaudio cannot be affected by standard admin/user. 'killall' kills the process and usually restarts it, and 'coreaudiod' is the process that does all of the magic that has to do with sound on a mac.

Check and see if there's a red light coming from the headphone socket, if so then it's got stuck in digital audio out mode. Try inserting and removing a headphone jack while wiggling it a little to see if you can release the small switch inside the socket (some have had luck with a toothpick but you need to be very careful doing that)

Try doing a Parameter RAM reset - hold down command/option/p/r keys at start up and wait for three chimes before releasing the keys.

I just got back from the Apple Genius Bar, and feel like a fool. The problem was that one of my sound settings was changed. I never thought of checking my settings, because I knew I hadn't changed anything, but it was as simple as that. Somehow "Built-in Input (Aggregated)" had been selected, and it should be set to "Internal Speakers".

I hope it's this simple for you, Eliza!

This works, at least until we get a patch from Apple

type the following on terminal (it will ask for your password)

sudo killall coreaudiod

Great!

The sudo killall coreaudioa seems to work, looking forward to get a patch for this!

Thomas

I posted previuosy but can't edit my old post for some reason., I was having the same problem on my iMac

Previously I stated that in my instance, in the Energy Saver Preferences, I had set the hard drive to sleep whenever possible. I de-selected this option, restarted and have had not had a sound problem for the first time in weeks.

I did experience the problem again where the sound card stops functioning and discovered that the problem is actually caused when the display goes to sleep. In my case, disapbling display sleep is the work-around for this issue.

I reported this as a bug to Apple.

Hope this helps somone else.

Peter

Hello - I just discovered this problem - no volume control, audio icon greyed out etc.

I used the terminal command you suggested which got sound back up right away (thank you!) but now my headphones won't work. When I plug them in, sound continues to come from the speakers. If anyone has any ideas about that, or what the 'sudo killall coreaudiod' command just did to my computer I would be very grateful!

Many thanks,

Br Stream

Thanks! This worked for me as well.

I tried the pram reset twice but mine still doesn't work. But it starts to work when i turn the bluetooth on.

IV Michael, thank you. Your suggestion about the red light in the headphone jack worked for me.

Thanks iVmichael -- this worked for me on a Macbook Pro Late 2011. The problem must've occurred due to re-installing the OS (Mavericks) recently.

Excellent... Thanks I fixed the problem!

The problem started last night after I disconnected a bluetooth speaker from the bluetooth icon in the menu bar. I didn't notice the problem until today.

FIX:

Re-connect bluetooth speaker

Go to sound settings (bluetooth speaker should be selected)

Select Internal Speakers

Turn off bluetooth speaker

Now my icon is not greyed out and I have control of it again. Hope that helps!