Last night I think I run all the latest updates on KDE Neon.

Now today when I start the system im stuck.

My second monitor is not recognized anymore. The Other one is stuck in 640x480.

What can I do?

I have had a similar issue. For me it's the nvidia graphics driver that isn't working correctly with the new update. I haven't found a fix for that yet, but I was able to use grub to boot up into the previous kernel, 5.0 and use my computer as before.

Hopefully there will be a better fix soon.

that did the job. Thank you very much.

HI!
the open drivers works fine, if you don´t need the propietary one