DISCLAIMER: this advice has worked for me many many times, but also has the potential to break the database, lock someone else out of their account, etc. if done incorrectly.
If you have access to the database for that site, you can reset the password manually with a query like this:
UPDATE `wp_users` SET `user_pass` = md5('new_password') WHERE `ID` = 1
You will need to change the '1' to whatever user ID your user has and 'new_password' to the text of your new password.
Also the table most likely is 'wp_users' but may have another name.