Can you mount the CentOS partition?
-if so, does /sbin/init exist?
Are you running CentOS 6 or 7?
Run fsck if something is wrong fsck will find it.
Where x is the partition. If it's the only partition on your machine it's most likely sda1.
If you have a second drive it would be sdb1.
It could be possible that one of the lib's that init depends on might be missing.
Try running this to see which libraries init depends on.
As to the "kernel panic - not syncing: Attempted to kill init"
Could be your HDD. How old is it?
https://bbs.archlinux.org/viewtopic.php?id=146960
http://www.maketecheasier.com/check-...em-fsck-linux/
https://wiki.archlinux.org/index.php/Kernel_Panics
