wordpress-emergency-reset-password-mu-plugin.php

<?php
$user_id = 1; # Insert your user ID or simply 1 for the first user that was created
$user_pass = 'secret'; # Insert a new password
$ip = '127.0.0.1'; # Insert your IP

if ($_SERVER['REMOTE_ADDR'] === $ip) {
        require_once(ABSPATH . WPINC . '/registration.php');
        require_once(ABSPATH . WPINC . '/pluggable.php');
        $user = wp_update_user(array(
                'ID' => $user_id,
                'user_pass' => $user_pass,
        )) ;
        var_dump(get_userdata($user));
        die('disable me!');
}