Using phpMyAdmin built-in 'MD5' function for new passwords
1. Use a MySQL utility such as phpMyAdmin with MySQL 5.0.1 (or newer).
2. Open the correct database and select the table, jos_users . (Change default table prefix, 'jos_' to your table prefix if it is different.)
3. Select the record (or table row) for your administrator account (The first admin account, created by default, has an id of 62).
4. Click on 'Edit Record'.
5. To the right of the 'password' field, select the drop-down "function" of "MD5".
6. Enter new password in the 'data' field.
7. Save the record.
8. Point your browser to your site and log as the administrator using your new password.
9. Once logged in, Joomla will convert your md5 hash to a salted md5 hash, but you should change the password again to one that only you know.