So, your sound isn't working.
Here are the steps that you should try to get the sound to work.
1. Are the audio cords plugged in? Try unplugging and plugging them back in. (Check the wall and your computer. Use Wall Unit Quick Start Guide to make sure you have the cords plugged into the right place.)
2. Is the sound on your computer turned on/up? (check in the upper right corner, on the icon that looks like a speaker) Sometimes, the sound will mute because of a bug with a sensor in the headphone jack. You need to unplug the audio cord, wait 10 seconds, then plug it back in. This should unmute the sound and it should work.)
3. Is the sound in the program turned on/up? (some programs, like iTunes or youtube have separate volume controls. Make sure these are turned on/up.)
4. Is the volume turned up on the wall unit? (See the Wall Unit Quick Start Guide for where the volume controls are located)
5. Is the mute on the wall unit on? (See the Wall Unit Quick Start Guide for where the mute button is located)
6. Is the sound amplifier in the ceiling set to video input? This can happen if the power goes out in the building. Press the PC1 button on the Wall Unit to switch to the correct input. (See the Wall Unit Quick Start Guide for where the PC1 button is located)
Hopefully this will fix your sound issues!