To reset your phpBB Admin password, please follow these steps:

A) Log into PLESK and do the following:

-Click Home
-Click on the domain with the phpbb installation
-Click "Databases"
-Click the database that contains the phpbb installation
-Click "DBWebAdmin"

B) Use phpMyAdmin to reset the password.

     1. Click the corresponding table that stores username and password information: phpbb_users
     2. Click "Browse" located towards the top of your screen so that a list of users display.
     3. Find the account of user that needs to be changed (ex: Admin)
     4. Click "Edit"
     5. From the user_password row, click the Function drop-down menu and choose "MD5"
     6. In the box to the right of MD5, replace the existing encrypted password with your new password in plain text
     7. Click the "GO" button located at the bottom of the page.

All Steps Completed, you should be able to log in with your new password, you may get prompted to login again with a securty code if you tried too many times.  Simply login again and enter the code if this occurs.