Didn't you made backups of your VMs?
Isn't that easy to copy a VM to a new drive. First you need both the virtual disk and the VM config.
The VM config is stored in the "/etc/pve/qemu-server" folder of your system disk. But that is not a normal folder, its a mountpoint of a special PVE filesystem that is based on a SQLite database. So if you can't boot your PVE this folder is just empty so you won'T be able to copy the VM config files.
Then there are the VM virtual disks. In most cases (LVM-thin and ZFS) these are not stored as files inside a filesystem, they are block devices and part of the LVM or ZFS disk management. So there is no file to copy.