How to change business (pvt limited company) firm name?

The first thing you have to find out whether the change of name (hwat you have choosen/preferred) has been available since if its already there again you have to opt another name (its like choosing an e mail id). You can find out from the Registrar of Companies' web site also. Depending upon the availability you can rename/change the company as you wish at the ROC office. The Certificate ofg incorporation to be obtained accordingly. The new name has tobe published in the newspaper to avoid any legal complexties in future.