We need to remove those non-focal repos:
sudo add-apt-repository --remove ppa:embrosyn/cinnamon
sudo add-apt-repository --remove ppa:noobslab/apps
sudo add-apt-repository --remove ppa:webupd8team/nemo3
You can check the package page - look for Focal release files.
sudo add-apt-repository --remove ppa:devacom/gnome-41
sudo add-apt-repository --remove ppa:devacom/x11
sudo add-apt-repository --remove ppa:devacom/gnome-40
Ok, once those are removed...
Run
sudo apt upgrade && sudo apt install --reinstall zorin-os-desktop
ok not running
Then what to do?
Please see the edit above - you still have standing gnome40 repositories that are breaking your package management.
Ok understand
Why this update not getting speed
My internet at 4Mbps
I'm not sure; may be heavy traffic on that bandwidth. I can only recommend patience for the moment.
Hopefully @Elegant_Emperor is still available to continue offering you assistance - I must step away from the computer for a while.
Okay, Thanks You Very Much Bro
Yep! 
I am seeing that for the first time!
Did any error message appear after the installation process in the terminal?
sudo apt install --reinstall gdm
Configure GDM by following the prompts in the terminal.
It's says gdm has no installation candidate
So I tried gdm3
Yeah that is alright.
Now what shoud I do?
Did the terminal give prompts to configure gdm?
No nothing happened
