Windows can't boot – How to backup wordpress' database?

This is a guess, since I don’t use windows. But if you can load Ubuntu and mount your directories then you’re getting there. It’s reasonable to expect that you might can get it back.

First look and see if there is anything in C:\xampp\mysql\data – if it isn’t there you’ll need to figure out where xampp was installed and get to that directory. Get into the mysql directory and locate the my.ini file. Open it and find the value of datadir – that’s where your data is stored.

As for restoring those files once you copy them to a safe location that’s a whole other animal.

Thanks for reply!! Yes, in in C:\xampp\mysql\data there are all files. How can I restore them, maybe in another PC with XAMPP? Thank you!

Yes, if you can copy that data to another machine and get XAMPP running with it you should be able to export your database.

I usually use this tool:

https://www.adminer.org/

Throw that in htdocs, you should be able to get it connected to your database and export it, then you’ll have everything from there in one compressed file ??