If you've lost the password to the Trend Micro OfficeScan web console, you can attempt to reset it to something known by editing a certain file using notepad.
Find the file C:\Program Files\Trend Micro\Officescan\PCCSRV\Private\ofcserver.ini. Open it with notepad and look for the parameter master_pwd. Change its value so the parameter reads:
Using this hash changes the root password to trendmicro. Restart the OfficeScan Master service (via Services) to apply the new password.
With newer versions (10.0), you may also have to edit the file C:\Program Files\Trend Micro\Officescan\PCCSRV\Private\AuthorStore\TrendAuthDef.xml, scroll down to the bottom of the file and replace the hash of the Pwd field with the one above. Replace only this value to avoid resetting the passwords of other accounts.