Chosen Solution
After my 12" Retina fell, my Audio Jack Board did not work when inserting a 3,5mm headphone. After replacing the Audio Jack Board as described here Retina MacBook 2015 Audio Jack Board Replacement it is not recognized by the OS, neither in Mac OS-X El Capitan nor in BootCamp under Windows 10 and therefore I have no sound at all. Any ideas???
Do you have any dents or scrapes when it fell and what did it fall on and how high? Also did you have the headphone jack plugged in. Open the Dictation & Speech control panel. Looking at the microphone icon can you see the level jump up and down as you talk or make noise? If not I suspect the ribbon cable got damaged connecting the Audio jack board to the main logic board.
