Letters all scrambeld - only 4

I have latest ubuntu release (20.04) with gnome fallback session. After reboot I got all letters scrambled. On desktop, in terminal, in explorer all files have only first four letters. I don't know how to describe it better. In firefox it's alright, menus have all letters.

It's like that:

Update: I tried solution from that page: https://forums.linuxmint.com/viewtopic.php?p=1996836

I did: sudo ppa-purge -d focal ppa:oibaf/graphics-drivers

Result: I can not get to Ubuntu any more...it's stuck on boot, just like in my previous thread: Ubuntu 20.04 stuck on boot

Solution 1:

I solved problem just like I did in the "stuck on boot" thread...I removed packages that were dependencies for xserver-xorg-video-nouveau, installed them, installed xserver-xorg-video-nouveau and instaled gdm3.