Here is a guide on how to reset the Joomla backend admin password

1. login to phpmyadmin using your Joomla database db_user and db_password, http://NAMASITE/webapps/phpmyadmin

2. select the database name in the left window, then select and click the jos_users table (if the default prefix is jos_)

3. click the Pencil image (Edit) on the username line that you want to reset the password

4. in the password field specify the desired new password, in the Function field give the MD5 function for your joomla user password encryption mode.

5. click Go to save the password.

Failed to log in as administrator, even though the password was successfully changed with a message:

• JAuthentication::__construct: Could not load authentication libraries.
• Username and password do not match

1. login to phpmyadmin using your Joomla database db_user and db_password, http://NAMASITE/webapps/phpmyadmin

2. select the database name in the left window, then select and click the jos_plugin table (if the default prefix is jos_)

3. click the Pencil (Edit) image on the Authentication - Joomla line.

4. in the published field change the value to 1 then click GO to save your changes.

5. edit the User - Joomla row still in the jos_plugin table change the published value to 1.

Unable to open the administrator page

Assuming you don't use a custome redirect to open the page http://namadomain.com/administrator/

but it's more about the plugin you're using, one of the plugins that we found to be the cause is System - jSecure Authentication.

1. login to phpmyadmin using your Joomla database db_user and db_password, http://NAMASITE/webapps/phpmyadmin

2. select the database name in the left window, then select and click the jos_plugin table (if the default prefix is jos_)

3. click the Pencil (Edit) image on the System - jSecure Authentication line.

4. in the published field change the value to 0

5. click GO to save your changes.

How to Reset Joomla Password Using PHPMyadmin

1. Please login to your cpanel...
2. From the cPanel menu, go to the PHPMyadmin menu.
3. Find the name of the Joomla database that you want to reset the password for, then click on the database name to access the database.
4. Jump to the "jos_users" table.
5. After finding the name of the user whose password will be reset, click "Edit" or draw a "Pencil" on the same line of the user whose password will be reset.
6. To change the password, select "MD5" in the function field and enter the new password on the right. Click "Go" to execute.
   
   
   
   Note:
   * If your joomla website is more than one, then to find out the database used by each joomla is by looking at the "configuration.php" file in your joomla website folder in the file manager.temukan baris berikut: var $db = ‘[USERNAME_CPANEL]_[NAMA_DATABASE_JOOMLA] ‘;
   *the table name customizes the prefix your database uses. ( jos_users = prefixdbanda_users )