Can't see grub loader menu after changing monitor, Plasma desktop also ceased to work
https://askubuntu.com/questions/1566365/cant-see-grub-loader-menu-after-changing-monitor-plasma-desktop-also-ceased-toGood day to everybody.
I have dual system computer with Windows 10 and Ubuntu 24.04.4 LTS with added KDE Plasma (installed by "kubuntu-desktop"). The computer has embedded (Intel® HD) and external videocard (NV108), the latter was used when installing Linux. The computer has worked fine until recently.
Yesterday I changed monitor to another one (with bigger diagonal) and mistakenly connected it to embedded graphics. Working with Linux was ok and GRUB menu was visible and allowed to select a system, but Windows ceased to work, it showed empty desktop, the mouse and the keyboard didn't react in Windows either (while worked in both Linux environments).
I realized that I had used wrong video output and changed it to external.
The first anomaly was that GRUB menu disappeared, but Windows started to work perfectly (it is indicated in GRUB_DEFAULT and starts due to GRUB_TIMEOUT). GRUB_TIMEOUT_STYLE is menu, so the menu must appear. Then I tried Linux, with the result that GNOME (default Ubuntu) desktop works normally, but Plasma desktop behaves as Windows formerly - empty desktop, the mouse and the keyboard do not react.
I tried "--reinstall kubuntu-desktop", but nothing changed.
I assume that problem may be associated with monitor, as the monitor is the piece of hardware that changed, but strangely that GRUB shows menu only while embedded videocard is used (so it must be tied with Plasma desktop that doesn't work either).
Would be grateful for any helpful suggestions to fix the problem.
