Macbook Pro.[Mid-2012] Sound isn't working

Something killed your coreaudio drivers, or the sound hardware/motherboard.

I would suggest to do following order of investigation (Fixes)

1. Open Activity monitor and look for following: (use sort by "Audio")

If found use terminal to reset the coreaudiod

sudo killall coreaudiod

2. Copy/paste following in Terminal to find out if the audio drivers are loaded

   kextstat > ~/Desktop/kexts.txt
   

   That will output a text file to your desktop. Use any text editor to search for "Audio"

   You should have the

   com.apple.iokit.IOAudioFamily   com.apple.driver.AudioAUUC
   

As reported the result is: AudioAUUC.kext is not been loaded?

3. Lets try to load it manually using Terminal sudo kextload /System/Library/Extensions/AudioAUUC.kext/

UPDATE:

Based on new information I would suggest following (still trying to find out why your Audio is not loading in the profile.

• Resetting the PRAM. Hold Down Cmd-Opt-P-R

Keep Holding until you have hear the "startup sound twice". If you do not hear the system sound then, you are on mute or your sound card is broken.

To un-mute use sudo nvram -d SystemAudioVolume

Test for start up sound!

• If not run ioreg -i and look for the AudioAUUCDriver <class AudioAUUCDriver, id 0x1000003af, registered, matched, active, busy 0 (0 ms), retain 5> (use Edit - Find AudioAUUCDriver)

In order to diagnose a hardware vs. OS error, try starting from external bootable media. The easiest way to do this is using a Linux Live CD. This allows you to start a totally separate, different and self-sufficient operating system. If you can get sound through that, it means the problem lies within your Mac OS X setup.

You can download a disk image here: http://www.ubuntu.com/download/desktop

If you can't or do not want to burn a CD or DVD, you can also make a USB drive. This can be automatically done using UnetBootIn (see: http://unetbootin.sourceforge.net ). You will need a fairly big USB drive and it will be formatted so make sure you have no files on it you want to keep.

I am suggesting Linux here because we also need to rule out a OS X-specific problem. Of some sort of EFI, HDA or OS X IOReg communication or matching failure causes CoreAudio not to load or to function properly, reinstalling OS X or booting form an external OS X drive might not help with further diagnostics.