I have tried to create a config file for my xserver with X -configure in the root shell (started ubuntu 14.04 in the save mode and selected root shell). But it puts out this Error:
(EE) Fatal server error: (EE) Could not create lock file int /tmp/.tX0-lock (EE) (EE) Please consult the The X.Org Foundation support at http://wiki.x.org for help (EE)