Originally Posted by mostafatalebi
I have installed CentOS 7. It was working fine until today that it hangs.
You've recently experienced the same problem with CentOS 6.4. In that thread as well as here it is not made clear what has happened (network and OS configuration, updates, etc, etc) since you installed the OS. You could try and boot a Live or installer CD, mount the partitions, save the log files (/var/log/*) and read them for clues. (Do use notepad++ or equivalent.)