[header] How to fix the sound on a mac computer [title] Restart the computer. [step] Sometimes a simple reboot will fix the audio issues you are experiencing. This should always be the first thing you try when something goes wrong. 
[title] Plug headphones in and then remove them. [step] If your volume controls are grayed out or you see a red light from your headphone jack, insert and remove an apple headphone plug a few times.