here the tricks of how to login ubuntu as root user…
Open the terminal and type:
sudo passwd root
When you see the prompt that says “Enter new UNIX password”, enter the password you want for the root user and confirm it.
Save the file.
Click other and type your user name: root, and enter the password of root you have set.
Thats it ………
***Note this is a bad Idea to do if you are connected to the Internet while logged in as root. Any malicious scripts execute themselves with out user permissions.