Mint not booting properly, sudo update does nothing

[np_parameter]

Linux Mint 20.3
I did something stupid via this link, purged, shut down laptop, turned on to see the following:

OK created slice system-system.x2dbacklight.slice.
Starting Load/Save Screen Backlight Brightness of backlight:acpi_video0...
Starting Load/Save Screen Backlight Brightness of backlight:intel_backlight...
OK Finished Load/Save Screen Backlight Brightness of backlight:intel_backlight.
OK Listening on Load/Save RF Kill Switch Status /dev/rfkill Watch.
system-backlight@backlight:intel_backlight.service
OK Finiished Load/Save Screen Backlight Brightness of backlight:acpi_video0.
system-backlight@backlight:acpi_video0.service
OK Started Show Plymouth Boot Screen.
plymouth-start.service
_

shut down, turned on, went to Grub > Ubuntu, with Linux 5.4.0-121-generic (recovery mode) > Recovery Menu (read-only) > network > got it to read-write, ok > dpkg

installed:
aptdaemon gir1.2-xapp-1.0 libxapp1 lsb-release mint-common mintsources
python3 python3-apt python3-aptdaemon python3-aptdaemon.gtk3widgets
python3-cairo python3-certifi python3-chardet python3-dbus python3-defer
python3-gi python3-gi-cairo python3-idna python3-pkg-resources
python3-pycurl python3-requests python3-six python3-urllib3 python3.8
xapps-common

upgraded:

curl libcurl3-gnutls libcurl4

resumed boot, got to tty.
sudo apt-get update fetches some metadata, sudo apt-get upgrade says nothing to upgrade.
shut down, turned on, nothing changed.
i'm stuck as to what i should do next to fix this mess. i'd like to save the files that are there and sudo installing a clean ubuntu desktop would erase those, (correct me if i'm wrong) so that's not an option for me apparently.

[Pjotr]

Restore a Timeshift snapshot. You can even do that from within the live session, after booting from a live USB stick with Mint on it.

[np_parameter]

i have no timeshifts. also my USB is gone.
i did sudo apt install cinnamon-desktop-environment and there's some progress, it boots to logo now but that's it

[Cosmo.]

There are several things, which I do not understand:

#1 How can somebody use the command on the linked page, although the page is flooded with warnings?

#2 Where shall the be the relationship between this attempt to destroy the own system and "USB is gone" exist?

[Pjotr]

FUBAR. I recommend a clean fresh re-installation of Mint.

[Cosmo.]

If USB is gone? Might get a unsolvable problem (at least, until the meaning of this gone USB is not cleared up).

[np_parameter]

There are several things, which I do not understand:

#1 How can somebody use the command on the linked page, although the page is flooded with warnings?

#2 Where shall the be the relationship between this attempt to destroy the own system and "USB is gone" exist?

i mean. i definitely learned something new. yes, it was stupid of me to do all of that
mint usb is just gone. i can get a new one yes, i can also do a clean install, but that would destroy my files

[Cosmo.]

mint usb is just gone. i can get a new one yes, i can also do a clean install, but that would destroy my files

Mh, if I understand now right, you say, that the usb stick is vanished, lost, but the USB-connector on the computer is working, Is this so?
I had at first understood, that you cannot use the usb connector for anything.

So you can boot into the live system. You could use Timeshift from there, but of course only in the case, that there is at least one snapshot. If there is none this is like a parachutist, who jumps without reserve parachute. No professional would do this, only suicide. One of the advantages of Mint is the case, that the reserve parachute is already build in. After a new install you get reminders about Timeshift from 2 other applications. Use it.

Back up all your data and do a fresh install.

[pbear]

In case it's not clear, you can use the live system to copy out your data files before reinstalling.

In addition to everything else on your new to-do list, add setting up a data file backup system. Timeshift for the system, something else for everything else. Options include Back In Time and Grsync (both available in Software Manager). There are others.

Never mind operator error. Hard drives fail, you know.