I know the question is about Lubuntu, but I hope I can still get an answer.
So, I had a Windows 10 laptop, on which I installed Lubuntu using dual boot. Everything worked fine, even when Windows basically got quite corrupted, and never bothered fixing it. I couldn't get to the system, but all my files were untouched, so they just stayed there. However, in a very silly manner, I deleted some of the Lubuntu system files, and it wouldn't boot properly, so I decided to reinstall it (all personal files on windows partition anyway). The installation would get stuck on something related to updating grub or finding another os, so I had to cancel the installation, but it would report installation was successful anyway.
I can boot using the grub command line, and get to the login screen. However, once I log in, there's only the wallpaper, the mouse pointer, and the trash icon (that when clicked would bring up PcManFm without the top bar with the program name and close, maximize and minimize buttons). No taskbar, key shortcut for the terminal does not work, and I am out of ideas, other than to delete the Windows partition and then install Lubuntu, but I want to keep these files, and I have no method of making a backup (there's about 500gb of data), and perhaps I'll want to fix windows in future (not right now).
Any help to run Lubuntu would be appreciated.
Edit: Some few thousand reboots later, the taskbar showed up somewhat corrupted, but the terminal shows up rectangles instead of characters. Then the system hung up, and I was forced to reboot, and now I don't have the taskbar yet again
Edit2: I can run Lubuntu live from a USB, so maybe I can do something from there?
Edit3: Perhaps I should mention it earlier, but the pc is running on 7y/o hard drive and giving errors on a bad sector