Volume/sound not working! Help??

[lindberg]

Okay, so last night I shut my computer with the headphones still plugged in, and now no sound will work. The volume image in the upper right hand corner is greyed out, as well as the pop up volume screen when I use my keyboard volume adjusters (there is also a circle with a line through it below the volume on the pop up screen).

Music won't start, youtube videos won't start, no thing having to do with sound will work!

I have been googling solutions, and the following I have tried and they have failed:
-Restarting computer
-Turning off computer, waiting, turning computer back on
-Software update
-Turning my computer off and holding down control, option, p and r at the same time (restarting PRAM I think is what that's called?)
-Downloading/installing Applejack (but I don't know what to do once I already have it installed AKA I don't know how to run the program

I am not tech savvy so I didn't quite follow some of the other suggestions given...

PLEASE HELP! I need audio for my studies.

[trevor]

While it's a good idea to run Software Update, and even to run Applejack when having some sorts of issues, I don't think that any of those steps with the exception of Zapping the PRAM is going to help with your problem.

The directions to zap the PRAM can be found here: http://support.apple.com/kb/HT1379 under the heading of "Resetting NVRAM/ PRAM".

Some other things that you can try:
1. plug and unplug the headphone jack in the receptacle several times.
2. if there's a red light coming out of the headphone jack, let us know
3. open up Audio-MIDI Setup (which is found in /Applications/Utilities), select "Built-in Output", take a screenshot of it's window, and let us see it

Trevor