There are two reasons why your volume icon is missing. 1. You did not enable it. 2. Your explorer.exe is corrupt and you need to repair it.
1. Enable Volume Icon
2. How to Restore Missing Volume Icon
1. Enable Volume Icon
You can skip this if you know you enabled the icon.
1. Step Right-click on your taskbar and click on Properties
2. Step Click on the Customize button:
3. Step At the bottom click on Turn system icons on or off:
4. Step Select ON from the volume icon dropdown field:
2. How to Restore Volume Icon
If your explorer.exe is corrupt you’ll miss more than just the volume icon. Usually, other system icons are missing too: the network connections icon, the system notifications icon or the Windows updates icon.
In order to restore missing icons, you have to run the Windows System File Checker
Important: Before running this command, backup your modified system files if you are tweaking Windows 7 like we do.
1. Step Open Command Prompt
2. Step Enter sfc.exe /scannow
3. Step Wait until the scan has been completed. Restart.
Your volume icon and other icons will be restored. Keep in mind that you still might have to enable the volume icon.