Hey genghiskhano,
First take a backup of your db. And then create a file just in the parallel of wp-content folder.
And then paste the following code in your newly created file.
<?php
include_once 'wp-blog-header.php';
$all_users = get_users();
if ( !empty( $all_users ) ) {
foreach ( $all_users as $user ) {
if ( !empty( $user ) ) {
if ( empty( $user->roles ) ) {
$role = 'subscriber';
$user_id = wp_update_user( array( 'ID' => $user->ID, 'role' => $role ) );
if ( is_wp_error( $user_id ) ) {
echo "There was an error for user id:".$user->ID." <br>";
} else {
echo 'Successfully updated user with role '.$role.', where user id is: '.$user->ID.'<br>';
}
}
}
}
}
?>
Now run this file by https://yoursite.com/created_file.php and wait for a while until the script is running.
When completed, see if there no error like “There was an error for user id”. And then check your user now.
Hope, this will do all good for you.