If you can not log in as administrator to the control panel of your Joomla website you can consult the following solutions to the most frequent issues that could cause a problem in order to regain access.
Wrong password
The first thing you should do if you can not access your Joomla website's control panel is to reset your password.
You receive an error message about JAuthentication
If you receive the error message,
JAuthentication::__construct: Could not load authentication libraries
Your username and password do not match, when you enter your login information then most likely the problem is caused because the Authentication - Joomla plugin is disabled.
To fix this problem you have to login to cPanel and find the phpMyAdmin tool under the Databases category. Once logged in to phpMyAdmin, select your database from the left menu.
Then you will see all your database tables from which you have to select the prefix_plugins table (the prefix is similar to what you have chosen during the Joomla installation process).
Find the Authentication – Joomla record and click the Pencil icon to edit it. You will see the preferences of this plugin, find the line named published and change it's value from 0 to 1. Finally click the GO button to save your changes.
Try to reconnect in your Joomla control panel to see if the problem has been resolved.
You entered the correct credentials but you return again to the login page
If you enter the correct login credentials, but you can not connect to the control panel and it returns back to the login page, then you need to check if the User - Joomla plugin is enabled.
To fix this problem you have to login to cPanel and find the phpMyAdmin tool under the Databases category. Once logged in to phpMyAdmin, select your database from the left menu.
Then you will see all your database tables from which you have to select the prefix_plugins table (the prefix is similar to what you have chosen during the Joomla installation process).
Find the User - Joomla record and click the Pencil icon to edit it. You will see the preferences of this plugin, find the line named published and change it's value from 0 to 1. Finally click the GO button to save your changes.
Try to reconnect in your Joomla control panel to see if the problem has been resolved.
These two Joomla plugins, Authentication and User, should be enabled in order to allow you to successfully obtain access the control panel of your website.
