Cannot boot end up always with a blinking cursor

I'm on Ubuntu 20.04 and it was working fine but after a recent reboot before which I had run some updates I can no longer log in as it never gets to the GUI login screen.

If I do Alt ctrl F2, I can login there but if I run something like startx that errors out and xrandr can't find any displays.

So I'm guessing this is a kernel issue? Any help/guidance would be appreciated.

Apologies for typos I'm writing from a phone

Success!

I was able to boot normally, with fully working system. What I did was installing mainline tool (method #3 from here → https://linuxhint.com/update_ubuntu_kernel_20_04/):

sudo apt-add-repository -y ppa:cappelikan/ppa
sudo apt update
sudo apt install mainline

(I had to edit sources list and change from groovy to focal)

Then I installed 5.9.12 kernel using Mainline installer and after rebooting everything worked fine (I saw that even earlier because my external monitor started to work while booting).

Additionally I've removed wireguard package because there was warnings while building GRUB images and since I don't use WG anymore I just uninstalled it. But I believe actual fix was delivered in 5.9 kernel.

I thought I'd add because I tried all these possible answers and it didn't work.

I have an old Nvidia GPU (GeForce 9600 GT) and I had to reinstall the display manager, reinstall the desktop environment and then reinstall the graphics driver. It seems that an update made the normal driver fail (nvidia-340) and I needed a different driver.

sudo apt install xserver-xorg-video-nouveau