Forget root password?! "Oh no!" "Oh my God!" "I'm dead man", "GGrrr!!...". So many expressions we have, if this had ever happened to us. Don't worry about that, take a deep breath..., drink a glass of water, pray, and do this :
Look what boot manager does our Linux use? Which one? LILO or GRUB ?

For LILO boot manager :

1. Press [Esc] when boot menu choice is displayed
   
2. Type "linux single" [Enter]
3. We are in Single User Mode, here.. we can reset our root password
   Type "passwd" [Enter] and set the new password twice (2x)
   Our root password has been changed
   
4. Reboot our computer to prove it, type "shutdown -r now"
   

For GRUB boot manager :

1. Press Button e when boot menu choice is displayed
2. Then choice the the option, there is word kernel
3. Press Buttonl e for edit
4. Add " 1" (spell: space 1) at the last sentence/command, like : xxxxxx 1
5. Press [Enter], then press Button b for boot
6. We are in Single User Mode, here.. we can reset our root password
   Type "passwd" [Enter] and set the new password twice (2x)
   Our root password has been changed
   
7. Reboot our computer to prove it, type "shutdown -r now"

Huraaayyy!!..... You're the master. The control is in your hands again