500 SERVER ERROR SUR MON SITE PRESTASHOP

Je n'ai plus accès a mon site hébergé sur ovh ni au Back Office.
Message "500 SERVER ERROR".
Après debug fichier "defines.inc.php" :

Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/leperenofl/www/config/defines.inc.php on line 143
[PrestaShopException]
Link to database cannot be established:SQLSTATE[HY000] [2002] Connection refused
at line 102 in file classes/db/DbPDO.php

97. public function connect()
98. {
99. try {
100. $this->link = $this->_getPDO($this->server, $this->user, $this->password, $this->database, 5);
101. } catch (PDOException $e) {
102. throw new PrestaShopException('Link to database cannot be established:'.$e->getMessage());
103. }
104.
105. // UTF-8 support
106. if ($this->link->exec('SET NAMES \'utf8\'') === false) {
107. throw new PrestaShopException('PrestaShop Fatal error: no utf-8 support. Please check your server configuration.');