open "SQL" console and type the next query:
UPDATE [YOUR_TABLE] SET [YOUR_TABLE].password= md5('[YOUR_PASSWORD]') WHERE [YOUR_TABLE].username = 'administrator';
In this - replase [YOUR_TABLE] by your realy table name, where are you login data.
And replase [YOUR_PASSWORD] by your real password. Quotes in md5 function should stay on query.
and try log in with new hashed password..