Untitled

<?php
 return array(
   'index' => 'Homepage',
   'feedback' => 'Feedback'
   'logout' => 'Logout from profile',
 )
?>

<?php
 return array(
   'logout' => 'Выйти из профиля',
 )
?>

$lang = include('lang/en.php');
if(isset($_GET['lang']))
{
   $lang = array_merge($lang, include('lang/ru.php'));
}

Array
(
   [index] => Homepage
   [feedback] => Feedback
   [logout] => Выйти из профиля
)

function __($name) {
    global $lang;
    return $lang[$name];
}

...
<title><?=__('index')?></title>
</head>
<body>
<?=__('feedback')?>

$file = file_get_contents("/path/to/file");
$lines = explode('r', $file);
foreach($lines as $line) $message[substr($line, 0, strpos($line, ','))] = substr($line, strpos($line, ','));

1,The site is down.
2,Try again.
3,No soup for you!
4,Signs point to yes.

$defaultLang = array('Home','Logout',etc)
$otherLang=array( 'ru' => array('Home_in_ru','logout_in_ru',etc);

echo translate('Home');

function translate($msg) {
    if ($_GET['lang']=='en')
        return $msg;

    return $otherLang[$_GET['lang']][array_search($msg,$defaultLang)];
}