iMac internal speakers not working, please help.

Go to System Preferences, Sound and then check if the output is set to "internal speakers"...

 

Is there a red light coming out of the audio out port?
If so plug and pull the TRS (3.5mm) connector of your headphones until it disappears.

 

Yep, this can happen as well, since the digital and analog sound connections are together...

 

So this is the problem that the other poster indicated...your digital audio connector got stuck...insert the headphone again until it disappears.

http://www.mac-forums.com/forums/ap...ok-pro-red-light-no-audio-problem-solved.html

Or here:

https://discussions.apple.com/thread/2257213?start=0&tstart=0

 

Look directly into the hole. It's not very bright. Turn off all the lights and put your hand right behind the hole and see if you can see anything on your hand.

Yes, there's supposed to be a switch that disengages. You could try a toothpick if you're brave. Or you could take it to the Apple store.

 

Thank you re: the switch in the earphone socket

I used a paperclip. It works fine now. So glad I don't have to go into the Apple store.

 

Have you tried using a different headphone jack? I had that same issue with my mac. Tried plugging/unplugging the headphone jack and it always stayed in mute mode. And all I did was use a different headphone jack and resolved it.

Hope this little piece of information works out for you.

 

Had exactly this issue on a 2009 27"iMac, nothing was working until I simply blew into the headphone jack. Might work for others...?