This is not the normal "black screen"issue and I was shocked to eventually find out why. The normal advice of reconfiguring Xorg didn't work. Even booting into "Recovery Mode" did not help.
Here is the short end of the stick that fixed it:
sudo apt-get install mdm mate-desktop-environment
Yes you got it right, mdm and the mate-desktop-environment / gnome were somehow uninstalled. This must be whe........
#solution
Edit /etc/yum.repos.d/openvz.repo
For the first two entries comment out #mirrorlist and uncomment #baseurl and then it worked
openvz yum problem Centos 6.5 cannot find file on mirror:
yum update
Loaded plugins: fastestmirror
Determining fastest mirrors
* openvz-kernel-rhel6: mirrors.ustc.edu.cn
* openvz-utils: mirrors.ustc.edu.cn
base ........
Jan 16 04:02:03 centosbox syslogd 1.4.1: restart.
Jan 16 04:07:34 centosbox kernel: INFO: task updatedb:20771 blocked for more than 300 seconds.
Jan 16 04:07:34 centosbox kernel: "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
Jan 16 04:07:34 centosbox kernel: updatedb D F78BE050 6476 20771 20766&n........