goldmelodyvn

Summary work for me:
Add the code follow in header.php of your theme:

<?php
// for multilanguage change flag
if ( function_exists( 'ps_012_multilingual_list' ) )
{
	$gs = ps_012_multilingual_list(false);
}
foreach(array_reverse($gs, true) as $key=>$val){
		$flags_dir = get_bloginfo('template_directory');
		$flags_dir .= '/images/flags/';
		$flag_icon = $flags_dir . $key . '.png';
		if ( ps_url_exists( $flag_icon )):
			if ($val['current']) {
				$flag_icon = '<img src="'.$flag_icon.'" style="float:right;margin:2px;border:1px solid #021a40;background-color:#ff0>"';
			}
			else
			{
				$flag_icon = '<img src="'.$flag_icon.'" style="float:right;margin:2px">';
			}
		endif;
		$html .= '<a href="'.$val['url'].'">'.$flag_icon.'</a>&nbsp';
	}

	echo $html;

?>

Copy folder at: wordpress\wp-content\plugins12-ps-multi-languages\flags to wp-content\themes\yourtheme\images