Unable to log into Ubuntu

I have Ubuntu 12.04.1.
Last time I did nothing especial, but suddenly some problem appear:
I have a login screen (using lightdm), when I attempt a login, I get a console session and returned to the login screen. I have same problem if I try "Guest session".
I see that it is a known issue, so I tried everything from following steps:
I succeed to to login with my account in console mode (ctrl+alt+f1)
I checked, and I don't have problem with disk space
I removed .XAuthority
I configured to use gdm
I reinstalled lightdm
I included my user to nopasswdlogin group
But nothing help...

So, these are errors from /var/log/auth.log in this step:

Oct  3 01:11:48 alphabet-2 lightdm: pam_unix(lightdm:session): session opened for user lightdm by (uid=0)
Oct  3 01:11:48 alphabet-2 lightdm: pam_ck_connector(lightdm:session): nox11 mode, ignoring PAM_TTY :0
Oct  3 01:11:48 alphabet-2 lightdm: pam_succeed_if(lightdm:auth): requirement "user ingroup nopasswdlogin" not met by user "andrey"
Oct  3 01:11:48 alphabet-2 dbus[704]: [system] Rejected send message, 2 matched rules; type="method_call", sender=":1.35" (uid=104 pid=1709 comm="/usr/lib/indicator-datetime/indicator-datetime-ser") interface="org.freedesktop.DBus.Properties" member="GetAll" error name="(unset)" requested_reply="0" destination=":1.14" (uid=0 pid=1169 comm="/usr/sbin/console-kit-daemon --no-daemon ")

After I reconfigure lightdm new .Xauthority file appear with root as owner, I put my user as owner and gave 777 permissions. The result is: when I try login, lightdm hangs on login process, it just stop and don't do nothing, I even can't press on screen buttons or change password, it just hangs up.

GDM also hangs up.

And these are errors after I get permissions for .Xauthority:

Oct  3 01:11:48 alphabet-2 lightdm: pam_unix(lightdm:session): session opened for user lightdm by (uid=0)
Oct  3 01:11:48 alphabet-2 lightdm: pam_ck_connector(lightdm:session): nox11 mode, ignoring PAM_TTY :0
Oct  3 01:11:48 alphabet-2 lightdm: pam_succeed_if(lightdm:auth): requirement "user ingroup nopasswdlogin" not met by user "andrey"

Any ideas?

Check that the file .Xauthority, is owned by your user, not root. You can change it by doing the following when logged in as root in your users home directory:

chown andrey .Xauthority

The key message is:

requirement "user ingroup nopasswdlogin" not met by user "andrey"

It seems that your system recently downloaded updates that affected the PAM system. So, if you log in as root and create a password for user andrey using the following command:

passwd andrey

then most likely you will be able to login.

Run the following command:

apt-get install gnome-session-fallback

Then use gnome classic (with or without effects).