Root password asking for authentication is required to change user data

Question

10. When I'm going to set ip address and click on save its showing "authentication is required user data" the its asking "root password" though I've no root password. I've single user account thats it. But I'm getting the same message when I'm going to "unlock" user account its also raising the same message though I've no root password only system password with which its showing wrong password. So can anyone please help me how to short out that. Its very very urgent for me now.