A few words of thanks would be greatly appreciated.

Windows - Error message: No active mixer devices available

Issue

Upon opening the volume control, the following error message is displayed:
"There are no active mixer devices available. To install mixer devices, Go to Control Panel and Other Hardware, and then click ADD HARDWARE."

Solution

Check if the Windows Audio service has not been disabled

Click on Start and Run
Type
- ```
services.msc 
```
Scroll down to Windows Audio and double-click on it
Set the Startup Type as Automatic and click on the Start button under Service Status.
Save your changes and restart your PC.

Thanks to jack4rall for this tip!