Hello @Padum, welcome to this forum.
You might consider following the highlighted advice:
First of all: Don’t panick! If the update was somehow buggy or faulty, there’s a good chance that there will be a new update as a fix in the matter of hours or days.
Using Linux means “taking charge”. You’re the boss. With great power comes great responsibility. This includes, as @Akito mentioned, making sure that your data is backupped safely before you make any changes. There are a lot of tools to make this an easy thing, like timeshift as mentioned by @edgrin2.
Some distributions take this a step further. E.g. Garuda always automatically creates a snapshot whenever you update your system and offers to restore it to a previous state right from the boot manager which is useful if you messed things up in a way that you can no longer boot into your operating system1.
However, as you asked how to restore or secure your data, I assume, you didn’t prepare for any failures. So, if I were you, I’d take the following steps:
- Store my
/home/minafolder on an external drive and I’d do the same with any other data I don’t want to lose. - Wait a day and try to update again.
- Do a fresh install, make sure, I have a backup strategy for the future and restore my personal files from the external drive.
1Is there any other distribution with this feature enabled by default? I don’t want to feel like I am constantly advertising.