Look at the logs to determine where problem exists. After failing to return to the graphical desktop, look at /var/log/Xorg.0.log to see if the X server started. Look at /var/log/gdm/:0.log to see if the Gnome desktop failed to start. Use dmesg or examine /var/log/messages to see if some other error occured.
"Never let the task you are trying to accomplish distract you from the study of computers."