服务器下载index.php而不是执行laravel

after one month of deploy my site in host and working normally. now i can't access in any page i get download index.php ?? why and how i can fix that ?

index.php

<?php

/**
 * Laravel - A PHP Framework For Web Artisans
 *
 * @package  Laravel
 * @author   Taylor Otwell <taylor@laravel.com>
 */

define('LARAVEL_START', microtime(true));

require __DIR__.'/../vendor/autoload.php';


$app = require_once __DIR__.'/../bootstrap/app.php';


$kernel = $app->make(Illuminate\Contracts\Http\Kernel::class);

$response = $kernel->handle(
    $request = Illuminate\Http\Request::capture()
);

$response->send();

$kernel->terminate($request, $response);

Check this 2 things.

1. You have php installed on your server, php -v on the terminal
2. The directory index for the web-server ex apache this can be on the main configuration or in a virtual host.

DirectoryIndex index.html index.php