When you are back, please reset the SMC and PRAM one more time. Then reset the coreaudio drivers of your Mac.
To do that, open Terminal from Applications > Utilities folder. Type the following command and press return
sudo killall coreaudiod
Then restart your Mac and immediately hold down Shift key on your keyboard for 20 seconds and this will boot into safe mode. Go to System Preferences > Sound and does it recognize the output controls ? Try to play something and can you hear ?
Also unplug all external sound devices if any connected and check. If it still not working, then we can reinstall the OS X. If this is a software glitch, reinstalling the OS X will fix it.
Restart your Mac and immediately hold down Command and R keys at the same time for 15 seconds and this will boot your Mac to the Mac OS X Utilities screen. From there, click Reinstall Mac OS X. Then follow the instructions to reinstall your Mac OS X.
If that didn't work, then restart your Mac and immediately hold down Command, Option and R keys at the same time for 15 seconds and this will boot your Mac to installation screen. Follow the onscreen instructions to reinstall.
(Reinstalling the OS X won't delete any of your files. But I'd recommend to backup all your important files to an external hard drive before reinstalling the OS X)
Please let me know if that didn't work, so we can continue troubleshooting.