A bit late, but maybe someone else can use this.
If you can still access the SiteBuilder database the following can fix it for you:
Here is a default hash in 'pswd' column for default password ('sitebuilder')
mysql> select * from sb_users;
+----+-------+------------------+------+------------+---------+
| id | login | pswd | role | createtime | sb_type |
+----+-------+------------------+------+------------+---------+
| 1 | root | 35cafb7a7a7ea2ff | 1 | 0 | 1 |
+----+-------+------------------+------+------------+---------+
1 row in set (0.02 sec)
So, you need you run following query:
mysql> update sb_users set pswd='35cafb7a7a7ea2ff' where id=1;
Now login to sitebuilder with user 'root' and password 'sitebuilder' and you're good to go!