View file application/routing/account/language.php

<?PHP
	if(isset($_SESSION['id'])) {
		$userSettings = new UserSettings;
		$userSettings->changeLanguage(
			$_GET['lang']
		);
	}
	else {
		$_SESSION['lang'] = $_GET['lang'];
	}
	
	if(isset($_GET['redirect'])) {
		Redirect($_GET['redirect']);
	}