My Macbook's headphone jack stopped working, how do I fix it?

Solution 1:

(posted as an answer so you can accept it and mark this issue resolved)

Have you checked the Sound pref pane in System Preferences? There's a tab labeled "Output" where (I'd expect, as I don't have a portable in front of me just now) you can switch output between built-in speakers and the headphone jack. If the first toggle doesn't work, toggle it again.

Solution 2:

The question is quite old now, but issue still remains on latest macOS (former OSX) version 10.12.4 Beta (16E163f).
One day I was using the headphones and the next day headphones jack port stopped working. Tried:

  • Reboot
  • Settings -> Sound -> "Use audio port for: Sound output"
  • Select headphones instead of any other thing on "device for sound output"
  • Reset NVRAM (previous PRAM)
  • Reset SMC

Nothing worked, then I tried to reboot with headphones plugged in, kind of worked, but if you unplug the headphones after rebooting, and then plug back in, it's not working anymore (it's kind of a workaround).

SOLUTION:
>> Shut Down -> Start MacBook and press CMD+R (Recovery Mode) -> Disk utility -> Select boot disk -> "First Aid" (both on the disk and the on the partition, did it also for the "Recover Disk Image", not sure if it helps) -> Reboot.

So far it's working fine.
Hope it solves your problem.

P.S.:What I was going to try next (not sure if it's possible) was to update/force reinstall audio drivers.

EDIT: It stopped working, and looks like it's not possible to reinstall audio drivers)
Workaround: Without the need to reboot or anything, just: plug headphones in -> close the lid (sleep) -> open the lid (wake)
Sound should now be coming out through the headphones.