public function connect($db_host, $db_username, $db_password, $mysql_db)
 {
     $mysqli1 = new mysqli($db_host, $db_username, $db_password, $mysql_db);
     if (mysqli_connect_errno()) {
         echo "Connection Failed: " . $mysqli1->connect_errno();
         exit;
     } else {
         return $mysqli1;
     }
 }
<?php

//Konexioa egin datu-basearekin
//$link = new mysqli("localhost","root","","quiz");
$link = new mysqli("mysql.hostinger.es", "u526113874_rb15", "123456789", "u526113874_quiz");
if ($link->connect_errno) {
    die("Huts egin du konexioak MySQL-ra: (" . $link->connect_errno() . ") " . $link->connect_error());
}
$balioak = $link->query("Select * from galdera");
?>

<!DOCTYPE html>
<html>
	<head>
		<meta name="tipo_contenido" content="text/html;" http-equiv="content-type" charset="utf-8">
		<title>Sign Up</title>
		<link rel="stylesheet" type="text/css" href="stylesPWS/estiloa.css"/>
		<link rel='stylesheet' 
		   type='text/css' 
		   media='only screen and (max-width: 480px)'
		   href='stylesPWS/smartphone.css' />
		<script type="text/javascript" language="javascript" src="funtzioak.js">
		</script>
	</head>
	<body>
		<div class ="nav" id="nav">
			<ul>
				<li class ="ezkerra"><a href ="layout.html">Home</a></li>
				<li class ="ezkerra"><a href ="credits.html">Credits</a></li>
				<li class ="ezkerra"><a href ="quiz.php">Quizzes</a></li>
			</ul>