This seems to be a pretty common problem. I'm working on my friends computer, because his headphone jack isn't working.
He has an Acer Aspire M, with a third-gen i5, 6GB DDR3, Windows 8 64bit, and a Realtek card.
He had been using headphones in the side jack, and they were working fine, but yesterday he plugged them in and they weren't recognized by Windows 8. I checked the playback devices in the control panel, and the default speakers is only reading one internal jack, no external jack. The headphones do not show up in the playback devices list. I installed the latest Realtek codecs, tried uninstalling the devices from the device manager, and checked in the Realtek control panel. Nothing seems to be working. I tried several sets of headphones in the jack, and it is the same deal. I did test his headphones in my computer, and they work perfectly.
I'm kinda at a loss for this...which is sad because I have my CompTIA A+. But any help is greatly appreciated.