How to reset the administrator password in Joomla
Normally, the super user can log in to the administrator control panel and reset anyone’s password in User Manager. But when the super user loses own password, then we have to reset this password in Joomla via the database.
Sure, you can first try the “forgot password” link in the administrator login screen …
But sometimes, the password was not forgotten. The super user could have been downgraded to “guest” by another super user or a malicious intruder.
In that case, follow the instructions on Joomla docs for creating a new admin user and then log in to fix the other super user. Creating a new admin user is useful also if you are working on a client site and don’t want to know the password of the client’s super user.
To access the database, you can use phpMyAdmin on the webhost. The database username and password and Joomla database prefix are found in the configuration.php file.
Depending on your version of Joomla (see how to determine Joomla version), run the appropriate SQL statement found in the Joomla doc. Make sure to replace with the correct database prefix. The SQL statement will contain the predetermined MD5 hashed password. There are three possible passwords to pick from. Pick one to put in your SQL statement.
Now you should login with this new admin (username = admin2) with the provided password. Change this password immediately as it is public knowledge to anyone who had read the Joomla doc.