The server was not allowing login to server even when ssh keys were saved
On rebooting server I could see it and error on screen “chown: Invalid username: root:Disk”
On troubleshooting found error to be due to corruption of /etc/passwd as this is where all users are saved and due to corruption the user root was missing in /etc/passwd
So I got the serve in single user mode and fastboot as only single user mode wont server and would restart
Once I got access to single user I just moved the /etc/passwd to /etc/passwd.bkp and copied /etc/paswd.OLD which was in /etc to /etc/passwd
Now on rebooting server i can see it working fine. :)