Hi Rainer, It sounds to me like it might be kwin that crashed, rather than Plasma. You can restart that with `DISPLAY=:0 kwin --replace` from any VTT.
> I can start new apps using the (former) K-menu, If you mean the Application Launcher, then that means you can run commands from there too. Either Luca's suggestions or `kwin --replace` (does not need the DISPLAY) hopefully work for you. Best, Thom