my sound isnt working after useing the headphone jack and i can see a red light in the outlet help!!

your mac still thinks the headphones are still plugged in. Try rapidly insterting and removing the headphones from the jack and see if you can flip the internal toggle switch. Other people may also recommend inserting a tooth pick in the hole to see if you can flip it that way.

The headphone jack internal switch has gotten flipped to the optical setting. The red light is the optical transmitter.

shldr2thewheel's suggested fixes are indeed the first things to try.

Try this link: http://kyen99.tumblr.com/post/8573258536/mac-os-x-lion-audio-fix

I had the same problem too and this app worked for me. It's a known bug in Lion.

I would advise against downloading that app. Also, your problem is not a known bug in Lion. It has to do with the internal toggle switch.

The app is intended for those who are not technical or new to Mac, the script is simply executing a "sudo" command in terminal to kill the "coreaudiod" process and to restart it again. I'm not sure why you think this isn't a bug or known issue. Try to Google it and see how many hits come up. Infact here is a link of a discussion that has been around: https://discussions.apple.com/thread/3220787?answerId=16849409022#16849409022

Try not to assume the worst. Especially if any one uploads a malware to another user on this discussion forum, Apple will know which account did it?...

At any rate, erinsharpie, I hope it is a software issue and not a hardware problem otherwise, I would definitely take it back to Apple. I wouldn't want to "Toothpick" every time the audio goes out...

Cheers...