1. Edit Grub Menu with press "e"
2. Find the line "linux" and add script below at the end of that line
rw init=/bin/bash
3. Mount with to see read/write flags
root@(none):/# mount | grep -w /
4. Reset Password with command below
root@(none):/# passwd
5. Reboot your system
root@(none):/# exec /sbin/init