This solution is the simplest and it can save you hours of effort so make sure you don’t skip this method when troubleshooting the Stereo Mix missing problem on Windows 10.
This automatically disables the use of Stereo Mix. This problem can also appear if your microphone is not available for access. Solution 1: Make Sure Your Microphone is Available for Access Audio driver – Stereo Mix is only available for drivers provided by your manufacturer and you will have to update them if you are using the default ones made by Microsoft.Stereo Mix is simply listed as disabled – Stereo Mix may simply be disabled as a virtual audio device in Sounds settings so make sure you simply re-enable it to resolve the problem.You need to allow apps to access your Microphone in Windows 10 Settings. The microphone is inaccessible – If your microphone device is not accessible for audio recording, Stereo Mix will be disabled as well.