Sound Issue - What happened here?

[beckyfailghost]

I own the latest version of an iMac, and my sound refuses to work.
However, when I start the computer up, it makes the long noise just before the gray pages with the dark gray apple comes up. But other than that, I have zero sound on the computer. I can't play my iTunes, nor can I watch youtube videos. Zip. Nada. No sound.

 

[sammich]

Have you checked to see if anything is plugged into the headphone plug/port on the back of your iMac? The startup sound always plays through the built-in speakers.

Double check in System Preferences -> Sound, Output tab, what is in that list?