i searched like hours, now i ask in this Forum.
How can I control the System Volume Setting of Windows 10?
Which Libary I need?
I am using Visual Basic 2015 and wanna programm a Windows Universal App with C#.
The programm should be able to:
- Set Systemvolume to x% 
- increase the Systemvolume by x 
- decrease the Systemvolume by x 
- get the current Systemvolume 
I found a similar Question and Answer, but the Answer doesent work.
private void Mute() {
        SendMessageW(new WindowInteropHelper(this).Handle, WM_APPCOMMAND, new WindowInteropHelper(this).Handle,
            (IntPtr)APPCOMMAND_VOLUME_MUTE);
    }
it can't find "WindowInteropHelper". But I implement:
using System;
using System.Windows.Forms;
using System.Runtime.InteropServices;
 
     
     
     
    