OH, I'M JUST KIDDING!
Download AND install the Audio driver
Driver: Small piece of software that allows the Operating System to communicate with a device
The device in question is the Audio chipset.
What version of Windows operating system was not stated.
Let's go to Dell Support,
Dell Support > Optiplex 360 Desktop PC > Main Support page,http://www.dell.com/support/troubleshooting/us/en/19/Product/optiplex-360
Click on the Drivers & Downloads - tab.
(Product Support / System Configuration / Drivers & Downloads / Parts & Upgrades / etc)
In the list click on - Audio (1)
Click on the blue -
Analog Devices ADI 198X Integrated HD Audio, V18.104.22.16853, A07
On the next page click on the blue - Download File
(To the Right of - File Format: / Update Package for Microsoft Windows)
Make SURE there is a Green dot in the small circle, to the left of -
Download and save the file
[IF not; left-click in the small empty circle, to the left of -
Download and save the file ]
Click on Continue in the blue oval.
On the next page make sure there is a Green dot, in the small circle to the left of - Single-file download.
Click on Continue in the blue oval
A small window will come up -
Click on - Save File
A small download window will come up.
Allow the file to download all the way, then DOUBLE-click right on the file name.
[If a Microsoft 'squawk box' comes up, ignore it. Click on OK, then on Run ]
At the bottom of the next 3 small windows, click on -
Next, Next, and Finish.
(DO NOT change anything. Just click on Next, Next, and Finish)
If you are not asked to restart your computer, do so. Close all windows, go back to your desktop screen, and restart your computer.
(Start > Turn Off Computer > Restart)
IF, you do not have the Volume icon in taskbar.......
(Time/Date is in the taskbar. A speaker icon is used for the Volume icon)
Click on Start > Control Panel
Click on > Sounds, Speech, and Audio Devices
Click on - Sounds, and Audio Devices
Go to where it states - Device volume in the middle.
(Blue in color, you are looking at the Sounds and Audio Devices Properties window)
Left-click in the empty square box, to the left of -
Place volume icon in the taskbar.
(Puts a Green checkmark in the box)
Now go below to the Right, and click on - Apply.
Then go below to the Left, and click on - OK
Close all windows, go back to your desktop screen.
Right-click on the Volume icon.
Left-click on - Open Volume Control
Make sure the volume slider is slid, all the way to the Top.
For additional questions please post in a Comment.