On install it asks the cookie name and you enter
phpbb3_fhjdh
In your settings table setting 171 should be /
settings 172-172 should be blank
setting 165 should be phpbb3_fhjdh
Now of course I am assuming here you correctly reinstalled entered the phpbb3 database info table prefix cookie name etc as if all that happens it would work.
You can email a url and admin login to support at photopost dot com
