I made an update on my packages and somehow something went really bad.
After the upgrade, it was not starting with my normal Linux, it only showed this:
error file /boot/vmlinuz-5.4-x_86_64 not found error you need to load the kernel first.
I was now going through this forum and repaired it with this tutorials:
I also had to delete and reinstall some stuff, now it works a little bit better.
but it can't mount now my encrypted root stuff.
error device /dev/mapper/luks-03xxxxxx not found skipping fsck mount /new_root no filesystem type specified
I found also reinstalled lvm2 like mentioned here but still the same problem.
I really hope, somebody can help me...