MySQL Issue

I installed cyberpanel on a ubuntu server. All were setup properly and working fine. Recently a client changed the control panel password and something else which he didn’t say. Now when I run following command it is showing following error:

root@server:~# mysqladmin proc status
mysqladmin: connect to server at ‘localhost’ failed
error: ‘Access denied for user ‘root’@‘localhost’ (using password: NO)’

I tried changing mysql root password by checking all available CP KB articles but was not able to resolve the issue. What am I missing here? What is the solution?