Problem : "I lost my root password after the installation ..."

Solve :
- Run Debian and press any key for stop autoboot at Grub selection
- Press "e" for start edit mode
- Add to the Kernel line (default, the line start with linux /...) init=/bin/bash (It's for run as root with Bash)
- Press "ctrl +x" or "F10" for start
- Run mount -rw -o remount /
- Use passwd for change your root password
- Reboot