No sound and volume icon I have a Mac mini and the sound has disappeared.  I have also lost the sound icon off the toolbar.  I went to preferences for the sound and see that mute is checked.  I can't un-check it because it is in gray-scale.  Any ideas?
Try to open the system preferences then click sound,on the sound you can see the Internal Microphone below the Name,on the lower,beneath the output you can see the Show Volume in Menu Bar,you can put some check on it and everything's gonna be alright :)