Many early generation macbook air laptops have had issues with the audio flex cable. People complain that they speaker icon is grey and does not show in black and all volume controls do not work. After some tinkering around with many commands, safe restarts, bezels deletes and other attempts to make the sound come back I somehow managed to make it happen!
I hope that you will have the same success and made a simple step-by-step video for you to follow. Please feel free to send me any D I Y videos and Id love to have them uploaded and shared for others to use and benefit from =)