How to Mount the Server in Rescue Mode

Login to Server (Rescue or Recovery Mode)

mount /dev/sda3 /mnt
chroot /mnt/ passwd root

or

mount /dev/sda2 /mnt
chroot /mnt/ passwd root


For RAID

=======
mdadm -As

then
mount /dev/md1 /mnt/
chroot /mnt/ passwd root