Help! No sound!

hi there.
basically my internal speakers are not working.
when i turn up the volume on on keyboard it has a stop sign (circle with a line through) and i thought it was on mute but it was not.
i looked on system preferences and on the output part it says digital out and built in output(it should say internal speaker) and the output volume at the bottom is faded so i can not change it.
any help is welcome and soon please!! =]

Try getting some headphones and putting them in and out of the headphone plug a few times, fixed the problem when that same thing happened to me.

This worked for me, thank you!