Unable to mount root fs on unknown-block(0,0), CentOS

If you test closer then one of your grub options is still working:

Solution is to boot with working kernel and reinstall kernel:

yum remove kernel-2.6.32-573.7.1.el6

Reboot and now it should work out of the box.

Now you can try again with new kernel:

yum install kernel-2.6.32-573.7.1.el6

reboot and celebrate!