Dinan101
This issue seems to plague the MacAir and no one seems to have the best answer. I was able to correct the problem on my daughter's MacAir by deleting the preference "bezel services". We previously replaced the audio cable and then the problem came back. Since deleting bezel services the issue has not returned for six months.
Here are all of the known steps to recover your audio. (copied from HighTechDad.com)
How to fix the “No Output Devices found” issue on your Mac:
Reboot – rebooting your computer is a tried and true method for “fixing” all sorts of problems (and it is not limited to just Macs, it works for PCs too!). Sometimes your computer simply gets confused.
Repair Permissions – this is a good thing to do regularly anyway, especially before and after you install new system software updates. Repairing permissions via the Disk Utility is something that is easy to do but can take a little bit of time.
Reinstall the latest OS X Software Update – this is a great fix for all sorts of issues as well. Go to the Apple site and download the latest Combo Update for your version of OS X. And be sure to Repair Permissions after installing the combo update.
Start in Safe Mode – try booting in “Safe Mode” by holding down the Shift key when starting up. Check to see if the audio is working after that. If it does work, there may be some other type of conflict going on and I would continue with the tips below.
Delete the BezelServices preferences file – this is a mysteriously magical file. It controls those on-screen images that you see when you change the volume, eject DVDs/CDs, change brightness, etc. But it also seems to be the source of all sorts of odd issues that you can never figure out, and tends to get corrupted. But the fix is easy and relatively safe. Go this preference file (location shown below) and just delete it and reboot. Location & filename:
~Library/Preferences/com.apple.BezelServices.plist
Plug in a USB headset – sometimes your Mac simply gets confused and needs to be literally poked by another audio output device. If you have a USB headset or speaker, plug that in and see if you get audio output through that device. If you do, that’s great! Then try unplugging the USB device and see if your on-board audio output device starts working. (Give it a reboot as well just to be sure it “sticks”).
Plug in standard headphones – the funny thing is, the fastest and easiest fix is the one that actually worked for me. I just took some headphones from my iPhone and plugged it into the headphone jack and magically the on-board audio output started working (it might have worked had I tried the USB headset fix above – but I couldn’t find one). This was another case of the Mac just needing to be prodded by something to get it going. I DON’T recommend sticking anything else into that headphone jack though (grin!).
I would love to find out what solution worked for you or if none of them worked. I saw plenty of threads on the Apple Discussion forums around this issue and it seems to happen to any type of portable Mac. If it still doesn’t work, you can take it the Apple Store to get fixed. If you have a MacBook Air, you might want to check out iFixIt.com for an Audio Cable replacement and install which you can potentially do yourself (but only for those who know what they are doing please!).
Remember, if you just keep digging around, you will eventually find a solution.
HTD says: Let me know if this did or did not work for you. Best of luck.
