Wordpress无法访问MySQL

My wordpress blog, hosted on my IIS 7.5 Server, suddenly lost his connection to localhost MySQL Database with no apparent reason. Both public and wp-admin links

Both public and wp-admin links throw an "Error establishing a database connection" exception.

I have successfully verified host name, user name and password opening a new ODBC connection with MySQL ODBC 5.3 Unicode Driver entering the credentials defined under DB_HOST, DB_USER and DB_PASSWORD at wp_config.php.

I've also verified database is not corrupted since I can successfully browse the database from MySQL Workbench 6.3

IIS 7.5 application pool is started.

I have tested wordpress connection with next code:

<?php
$link = mysql_connect('localhost', '(my user name)', '(my password)');
if (!$link) {
die('Could not connect: ' . mysql_error());
}
echo 'Connected successfully';
mysql_close($link);
?>

which throws next result:

Could not connect: php_network_getaddresses: getaddrinfo failed: No such host is known.

If I change localhost to 127.0.0.1 the code just returns

'Could not connect:'

and no error is displayed.

Any help will be apreciated