@TobiSGD:Thank you for the reply.
All the files that I edited (sudoers, shadow) are on a directory in the client.The server copies these files from the client into its '/etc' directory every time it reboots(like I have mentioned in the original post). In fact when I login into the server, I can view these changes that I made. The problem was once I am in the server it did not allow me to change the 'date' because I dont have the sudo rights, and logging in as root using 'su' also did not work as it was not accepting my password(or the password I mentioned in the /etc/shadow file). I am sorry if all this sounds very confusing,because it is
.. I dont know how I can explain it better.
All said and done, now the problem is actually solved, but only through a workaround! The root password was not working when I logged into the server with my user name and then gave the command 'su'. However the same password worked when I directly login to the server using:
'ssh <server.ip.address> -l root'
So I was able to login as root user on server and set the date with the above command. But I still can't figure out why this worked and the other method did not.