Plugin path comes wrongly

To solve this problem, we must use plugin_dir_url command.

For example:

<?php
                    wp_register_style( 'foo-styles',  plugin_dir_url( __FILE__ ) . 'dahili/bootstrap.min.css' );
                    wp_enqueue_style( 'foo-styles' );

?>

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)