Can't log in to ubuntu 12.04

Question

I can't log in to my ubuntu 12.04. Once I login I got returned back to the original screen after a trial to enable X11 Forwarding.

Can you help me with this.

Are you trying to login remotely? What did you do to try to enable X11 forwarding? — izx, May 19 '12 at 21:40
Does this only happen when trying to log in remotely? Or are you having this problem logging in locally as well? — Eliah Kagan, Mar 27 '13 at 1:07
Check your .xsession-errors in your home directory, I found an error over there, fixed it, then I can login from desktop. I did try to change the permission and ownership of .Xauthority but it doesn't help in my case. — user288195, Jun 3 '14 at 23:25

jokerdino · Answer 1 · 2013-09-11 14:42:24Z

I haven't tried to enable X11Forwarding, but I used to have the same problem. You can fix this in a few steps:

When you get to the graphical login screen, hit Ctrl+Alt+F2, thus you get to a textual login.
Put in your name and password (password is not displayed when you type, neither as stars or bullets).
Type sudo apt-get install gdm and hit enter, give your password and wait to get a line ending with a dollar sign again.
Type sudo dpkg-reconfigure gdm.
Hit Enter at the first screen.
Select gdm in the list you get in the second screen with the arrow keys.
Hit the Tab button (above the caps lock one). Now you see the word Ok highlighted. Hit Enter.
Type sudo reboot and hit enter. You'll get another graphical login screen, but you'll be able to log in!

P.S.:

If you are used to running some programs like ifconfig or others which are administrative ones from a terminal emulator (e.g. gnome-terminal) you'd better add a line like PATH="$PATH:/sbin:/usr/sbin" at the end of the .bashrc file in your home directory. You can do it with echo 'PATH="$PATH:/sbin:/usr/sbin"' >> ~/.bashrc.
If you want to change back to the other graphical login screen from time to time and see if it was bug-fixed and it works again you can run sudo dpkg-reconfigure gdm and select lightdm and reboot (doesn't look like it works if you just run sudo pkill X).

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