cannot login as root to install printer

Thank you for taking the time to report this issue and helping to make Ubuntu better. Examining the information you have given us, this does not appear to be a bug report so we are closing it and converting it to a question in the support tracker. We appreciate the difficulties you are facing, but it would make more sense to raise problems you are having in the support tracker at https://answers.launchpad.net/ubuntu if you are uncertain if they are bugs. For help on reporting bugs, see https://help.ubuntu.com/community/ReportingBugs.

I strongly suggest to use sudo command to run command as root user
(the powerful administrator predefined user of gnu ubuntu Linux)

You can use plain root access using the terminal command sudo -i but please don't do it use the sudo command as we always do.

So to run a command with root privileges pelase simply put a "sudo" before your command example:

sudo fdisk -l

Typing the commands using sudo the system will ask you for a password, please give your user password when requested, you don't see nothing when you type it, then press enter.

More details https://help.ubuntu.com/community/RootSudo

Hope this helps