AMPP by default uses http://localhost/phpmyadmin
It also requires you start both Apache and MySQL from the control panel (or as a service).
In the XAMPP Control Panel, clicking [ Admin ] on the MySQL line will open your default browser at the configured URL for the phpMyAdmin application.
If you get a phpMyAdmin error stating “Cannot connect: invalid settings.” You will need to make sure your MySQL config file has a matching port for server and client. If it is not the standard 3306 port, you will also need to change your phpMyAdmin config file under apache (config.inc.php) to meet the new port settings. (127.0.0.1 becomes 127.0.0.1:<port>)