Audio Output Problem I am trying to help my dad with his Mac (OSX 10.9.2), the problem seems to be with the audio (or lack-thereof). The internal speakers are working (since hitting F11/F12 keys makes the "Beeping sound" (Increasing/Decreasing audio)) but other than that there isn't anything from the speakers or headphones off of any other source of possible audio (Youtube, iTunes, etc).

The output type is selected as:


What causes this and what is the best bet for a fix?
Reset the PRAM as suggested by some other sources on the internet. Working well now.

1) Shutdown 

2) ⌘ + option + P + R before grey screen appears 

3) Release keys when you hear the "start up sound" for the second time

4) You may need to reconfigure some settings