I faced the same problem of not able to log into the ubuntu's root account. Ubuntu is more secure and it makes the user to make use of the resources safely, hence instead of providing the su command, it has provided sudo command. Using sudo you could log into the root account as follows:
bash#sudo bash
u get the root access to your new bash shell, now you give
bash#sudo passwd
Enter New Unix Password:
Confirm Password:
And BINGOOOO.... you now made a password for the root account :D enjoy by logging off the current user account and log into the root account with your currently set password :D
bash#sudo bash
u get the root access to your new bash shell, now you give
bash#sudo passwd
Enter New Unix Password:
Confirm Password:
And BINGOOOO.... you now made a password for the root account :D enjoy by logging off the current user account and log into the root account with your currently set password :D
