Forgotten root password
Well if you have forgotten your root password, then it is fairly simple to reset it.
When the computer is starting up, keep pressing the tab key to get to the grub menu, then press e to edit and then use the arrow
keys to scroll down and highlight the line that says kernel in it, then press e to edit again and add 1 to the end of the line, then
press b to boot, you will now boot to a command prompt, just type passwd and you will need to enter a new password you want
for root, then type shutdown -r now and your computer will restart with the new root password.
Just goes to show how easy it is for someone, if they have physical access to your machine, if your worried about someone stealing your comp etc.. then encrypting the drive would be much better security.