Macbook Air without Sound, and missing Input/Ouput device options
Shut down the Macbook 
Press  shift + ctrl + alt and press the power button. Notice the change in power led color if the Macbook is connected to power. Note this won't start the Macbook.
Now, press command + alt + P + R, and press the power button. You will see the screen flashing a couple of times. This won't power on the Macbook either.
Now, start the Macbook normally.
Enjoy!