Probably…
We can’t really know what happened to your system.
If you go the reinstall-way:
Backup you home folder as a whole.
Also make a backup of /etc /var/lib /usr/local/ /usr/share.
/home/yourusername holds ALL your personal data, including your personal settings, stored passwords, whatever…
/etc contains most of your system-wide settings, you may carefully restore them if you really need, but be careful! And don’t copy back these settings as a whole to your new system, otherwise you’ll brake it.
For example, if I had a custom setting of Samba, I just replace /etc/smb.conf on the newly installed system with the corresponding file from my backup.
And restore configs one-by-one, preferably rename the existing, currently overwritten configfile, something like .conf.bak. So for the example, I’d rename smb.conf to smb.conf.bak.
I hope you get idea.
Don’t restore /var/lib, and other directories, just use coule of stored files there only in the case you really need them! And do this carefully too…
At the end you’ll have a 22.04 based system which acts and behaves the exact same way as your previous system, and still gets security updates for years…
First, you should internalise the rule, that before you do anything, you should take a backup beforehand.
If you had a backup, you wouldn’t be in this situation right now. You could restore a backup, save your settings & files and then re-install or apply other fixes to the issue at hand.
Can I say to Rohit
Whenever you make system changes, keep notes on what you did.
It helps when something like this happens.
Use Timeshift or Systemback. I myself prefer systemback, because it is just a script, so it is usable on my servers as well on desktops.
Whenever I start to experiment with something, I take a snapshot of the healthy system. I can easily revert all changes in 2 minutes, if something goes really wrong.
Absolutely. One must have a backup before proceeding.
What I was referring to was taking hand notes or using script. It gives you some chance of fixing mistakes if you can remember what you changed.
Showing my age, I guess.
Thank you @Akito @nevj @kovacslt and @berninghausen for all the help. Much appreciated!
I’ll now start the process of installing 22.04.
This machine is my secondary PC and doesn’t have too critical data on it. Hence, I just blindly experiemented (honestly I thought, “these are legit/stable updates and won’t break my system” – but they did). But I totally understand your point.
On my way to 40s as well… 
Thanks again everyone!
Alright some update now: I used this link to update to 22.04 using command line (also learned during the process as to how to connect to wireless via CLI). The process took its time and eventually updated to 22.04. But it was Ubuntu Studio with Gnome. So I then again I manually installed KDE. It works fine now and almost all my key settings and docs are in place.
Only that AMDGPU drivers are broken so I’m unable to set brightness (it is on full brightness now). But I’ll try to figure something out.
At any rate, I now have:
- Ubuntu Studio 22.04 LTS
- My GUI back.
Thank you again people!