That's terrible, sorveltaja!

I've never had that happen or anything like it.
I would like to help, but I don't know the details of your installed system. I do suspect it is possible to fix it, but I'd need a lot more information to work with.
If I remember correctly you are running Mint in a virtual machine in a Windows system?
Okay, just as a start at recovery, would you be adverse in creating an EasyOS thumbdrive, and then booting from that so we can look at what's happening on your HD? I'm really most familiar with EasyOS and its tools for that.
To create an EasyOS thumbdrive, if you are able to get the following files into Mint (or any other Linux):
easydd makes bootable thumbdrives and installs an OS image to it:
https://bkhome.org/files/easydd.gzAnd the latest version of EasyOS (7.2):
https://distro.ibiblio.org/easyos/amd64/releases/excalibur/2026/7.2/Usage:
Just insert a USB thumbdrive of 4 or more Gb and start easydd. It will ask you for the location of the image file (the EasyOS 7.2 version you downloaded), and the thumbdrive name. The rest is automatic.
When done, you can re-boot with the USB thumbdrive inserted, and if your computer BIOS is set to be able to legacy boot from USB (before the HD) EasyOS will start up. Answer the first boot questions about country and keyboard, etc. and you'll be good to go.
Let me know if you do any of this, and we can go further.....
ps. If you can't use Mint (or other Linux OS) to download or run the above files, but you can still run Windows, you can use a program called USB-Image-Tool to write the EasyOS image to a USB thumbdrive. (It is not recommended that you use any other Win USB image writers ...like "Etcher").
USB-Image-Tool is available here:
https://www.alexpage.de/usb-image-tool/download/