No playback: no host found

I’m facing a strange problem:
Since I installed a new video card none of my audio programs can access the audio output any more, while all video programs still can.
I’m no newbie, I’ve tried everything the last days.
The new card came with an AMD audio driver, I uninstalled that already. “Speaker” button in taskbar: all possibilities checked. Roamed the net, no solutions for this special issue. Selecting the output of the audio programs: no useful effect. (WinAmp says “undefined external error”, the CoreMediaPlayer switched from “audio hardware not available” to playing silence, and so on.) It must be some trick about the audio paths.
Setup: Win10 on a hp PC, Realtek on-board audio, everything updated, all drivers latest version.
Stating again: All video programs can play audio (Win Mediaplayer, VLC, Davinci Resolve … ), and the standard computer sounds (“new email” etc) work, too. Only audio programs deny - all of them.
I attach a screenshot. As you can see, Audacity recognises the file well, but doesn’t show a host, so I have no chance to select anything.

Thanks in advance - hope you guys got any idea!
Screenshot Audacity.jpg