I lost my password to my account on a Serendipity blog recently, but still had access to the database. I did some code digging, and figured out how to reset a user’s password.
First, you have to figure out your install’s hash key:
SELECT name, value FROM s9yconfig WHERE name = 'hashkey';
Then, run this on the s9yauthors table:
UPDATE s9yauthors set password = sha1('hashkeynewpassword') where username = 'username';
So, if your hashkey is 1234, you would run:
UPDATE s9yauthors set password = sha1('1234newpassword') where username = 'username';
After that, I was up and running.