Sounds problems

Today out of nowhere my sound stopped working in my G4 powerbook. All the prefrences say that the sound is on full blast and i am not on mute. I don't know why the speakers are not playing the sound! I tried sticking some headphones in to see if they would work, and they did. I'm guessing it has something to do with the speakiers, but Idk. I'll leave it to you guys, the professionals to tell me. :bandage:

The same thing hapened to me. Probably after upgrading to 10.3.6, my sound is gone, no output no input. Resetting the PRAM produces the start-up tone once, so I think the sound hardware should be ok. But no sound once the computer has finished starting up. Now, even the start-up sound is gone, too. Can anyone help?