I use Intel and AMD, but as far as I know, there is a problem if you change to the Intel one in the GUI. You cannot change back to Nvidia later. The solution is simple for that. You can change it through Terminal. After a restart it works normally again. Actually, this should be an Nvidia bug, Ubuntu is not to be blamed for it.
I am not sure whether you meant this as your problem or something totally different.

I tried it with command prime-select nvidia and prime-select intel bat sadly they don't work. I think the only solution is to fresh install the system...

I got something like this on my laptop with Linux Mint. Sometimes its Nvidia card stopped working (usually after upgrading Linux kernel) but it was fixed on the next boot. Recently I had a problem with 396 driver on my main computer, it just didn't work. I solved that by full reinstalling of Ubuntu. It probably was a mismatch between old and new configs or something.

You wrote "I tried to purge all nvidia*"
Thast will only get all packages that start with nvidia in the name, but there is also xserver-xorg-video-nvidia-390 and xserver-xorg-video-nvidia-396 and maybe more.
So you would need a

sudo apt-get purge nvidia-*

sudo apt-get purge *nvidia-390

or even just

sudo apt-get purge *nvidia*

Also install ppa-purge,
sudo ppa-purge ppa:whatever/ppa

and some useful commands to debug:

gpu-manager

that will show what it is trying during the boot regarding setting up the gpu, what drivers are loaded, blacklisted and so on

dmesg

gives kernel messages

journalctl -b

all system messages since last boot

inxi -G

will show info about your graphics, GPU, OpenGL driver, kernel modules and so on. Install it with sudo apt install inxi

And

sudo ubuntu-drivers autoinstall

will do the same as adding drivers from additional drivers, but you can do it from the commandline