Hi this is my first question on this forum. I am using ubuntu 12.04 LTS. After installing an Auto-complete plugin for Gedit and changes in $HOME/.gnome/gedit/plugins/ , i now can't login as my root. the login screen re-appears after username and password prompt.
I can use all tty , guest account.

I had the same problem, I still cant log in to my original user. I got around that problem by log in to another tty session and created another user a number two version of my original user. Then I put this new user in all the same groups as of my original user.

I know is not a solution, just a work around.
you can created another user with the command useradd
created a password for your new user with the command passwd <newuser>
and add the user to the groups

post more questions about how to do that I am sure many users here would give you a good advice

Good luck to you!

Hello and thanks for the Reply.
Luckily i found a solution. First i logged in as tty1 (ctr+alt+1), with my credentials that were causing me the problem.

I undone previous changes i.e. rm -rf $HOME/.gnome2/gedit/plugins/* and then followed some steps given in this link http://askubuntu.com/questions/18441...-compatibility

ls -ld .Xauthority
sudo chown -R $YOUR_SUDO_USERNAME:$YOUR_SUDO_USERNAME .Xauthority

and luckily it worked for me and now the login screen does'nt complain.

Thank you I fixed too, however all I had to do is log in on a new tty session with Ctrl+Alt+F2
type the user name of my original user then password and type there
Hit enter, type my password and hit enter again.
Then log out and press Alt+F7 to log out and log back in with my original user and it worked fine.