If you have access to phpmyadmin you can replace password hash like:

for password: zaq!@WSX hash is

c1ce38227c8fc3aff37accf8fc31263e



in database table prefix_member password row

PBBoard use MD5 hash so you can genarate hash for your new password on this site:

http://www.miraclesalad.com/webtools/md5.php



:)