The root account for Ubuntu is disabled by default. To use root privileges, you are required to use the 'sudo' command. It is possible to always use the root account by following the steps given below.
Launch the terminal and issue this command to set a password for the root account:
sudo passwd root
To log in as root, issue now this command:
To disable the access to the root account, you need simply to run this command:
sudo passwd -l root
Tested under Ubuntu 10.04/10.10/11.04