Help repairing GRUB on LUKS-encrypted volume

[LinuxNewbie]

Hello!

I'm dual-booting using two separate drives; one using Kubuntu 25.10 and another using Windows 10.
However, yesterday when I tried booting to my Kubuntu drive, my PC booted straight into Windows 10 and continues to do so.
Normally, it would boot into the GRUB menu where I can select between the two systems, but not this time.
This leads me to believe that GRUB has been destroyed, since unlocking the drive using a live USB shows an empty GRUB folder in root.
My Kubuntu install has two partitions: sda1 (ext4, kubuntu_boot), sda2 (luks2, root).

I've tried changing the boot order in my BIOS, as well as unplugging the Windows drive, but when I do this, my PC finds no bootable drive.
I believe I need to follow the guide linked here, but there's a few things I don't understand about it:

sudo -i
apt-get update
apt-get install cryptsetup lvm2
fdisk -l
cryptsetup luksOpen /dev/sda? TAG # sda? is your root partition
vgchange -ay
vgscan
vgchange -ay [VOLUME GROUP NAME] # From the above command
lvscan
mount /dev/[VOLUME GROUP NAME]/[LOGICAL VOLUME NAME] /mnt # LOGICAL VOLUME NAME from above command
modprobe efivarfs
mount /dev/sda? /mnt/boot/efi # sda? is your efi partition
mount --bind /dev /mnt/dev
mount --bind /dev/pts /mnt/dev/pts
mount --bind /proc /mnt/proc
mount --bind /sys /mnt/sys
cp /etc/resolv.conf /mnt/etc/
chroot /mnt​

What is [VOLUME GROUP NAME] and [LOGICAL VOLUME NAME], and where can these be found in the terminal?

Thank you!

[LinuxNewbie]

Is anyone able to help?

[claydoh]

What is [VOLUME GROUP NAME] and [LOGICAL VOLUME NAME], and where can these be found in the terminal?

The example tells you

vgchange -ay [VOLUME GROUP NAME] # From the above command

which is vgscan

Also note this is quite old, and may not be valid today, or not completely. It *looks* okay, but I haven't used encryption regularly in ages, on any distro where it didn't break.

As this sort of thing isn't specific to Kubuntu, you may find more people who actively use this or have had similar issues on a general Ubuntu support resource, in addition to whatever experiences are reported here.

[LinuxNewbie]

The example tells you


which is vgscan

Also note this is quite old, and may not be valid today, or not completely. It *looks* okay, but I haven't used encryption regularly in ages, on any distro where it didn't break.

As this sort of thing isn't specific to Kubuntu, you may find more people who actively use this or have had similar issues on a general Ubuntu support resource, in addition to whatever experiences are reported here.

I tried with vgscan, but it didn't work, unfortunately.
Thanks for the answer, I think I'll see if someone has a solution on Ask Ubuntu.
I hope I won't have to reinstall, but if I did, couldn't I overwrite my new root with the files from my old one?