Ubuntu 18.04 Sudden Duration Charging Screen?

I've been working with an Ubuntu system for a few months now. Everything has worked so far.

Only since today the system can't be started. I turn on my laptop, then comes the Ubuntu Charge Screen and it does not disappear anymore. Everything was still going on yesterday evening. I also did not update or install or uninstall other programs. Even turning off and restarting does not work.

It would not be a big deal to rebuild Ubuntu because the files are backed up. Would be stupid, however, because I would have to install dozens of programs.

Especially yesterday everything went wonderfully. That irritates me.

What can I try so that the system starts normally again? Not that I reset the system and that it happens again.

Info: I use Ubunutu 18:04 on a Lenovo Thinkpad Edge E535 (older).

I would reinstall Ubuntu with a boot stick and keep your Dazem (is queried during installation) otherwise I have no idea and assume no liability for your data

I have the data yes, that's no problem. Only I have little desire to download the whole program again, partly done by a colleague and do not know what I specifically need everything to just continue with my work.

But it would be possible to reinstall and the programs are still on it?

Press ESC times, then the boot messages should appear, which may give you a hint, where it depends.