MacBook has no sound output
I have a MacBook running Snow Leopard (v. 10.6.8).
I am not getting any sound (output), except the chime when powering on.
The speaker icon at top of the screen is greyed out and the volume slider doesn't work.
Sound output 'preferences' reports "The selected device has no output controls" for the optical digital output port.
What's the fix for this (and why is it happening)?
Thanks.
MacBook, Mac OS X (10.6.8), 1.83 MHz