sshd is part of the operating system, not part of cPanel. If /etc/ssh/sshd_config is changing without your knowledge, then you need to consider who else might have root access to your server and be able to change it. If /etc/ssh/sshd_config is literally becoming corrupt, as you say, then I would recommend rebooting the server into single-user mode and running an fsck (filesystem check), as well as doing hardware diagnostics on the hard drives.
Your data center should be able to help you with all of this, because sshd is not part of cPanel, and keeping the server online and accessible is a responsibility of the data center.