Sometime, you want to display posts outside of WordPress. Here are some resources to help.

From the Integrating WordPress in your Website codex file, the first place you start is to include a WordPress header file:

<?php
define('WP_USE_THEMES', false);
require('/the/path/to/your/wp-blog-header.php'); //found in the root of your WordPress install.
?>

If you are using a multi-site blog, you will also need to add the below under the include:

switch_to_blog($blogID);

From the codex, the quickest example of showing a postis the following code:

$posts = get_posts('numberposts=10&order=ASC&orderby=post_title');
foreach ($posts as $post) : start_wp();
the_date(); echo "<br />"; the_title();
the_excerpt();
endforeach;

Using the WPQuery function, you can target the number of days to show. The codex has the example code:

// Create a new filtering function that will add our where clause to the query
//from: http://codex.wordpress.org/Class_Reference/WP_Query#Time_Parameters
$args = array(
'post_status' => 'publish'
);
function filter_where( $where = '' ) {
// posts in the last 30 days
$where .= " AND post_date > '" . date('Y-m-d', strtotime('-30 days')) . "'"; //change 30 to the number of days you want
return $where;
}
add_filter( 'posts_where', 'filter_where' );
$query = new WP_Query( $args );
remove_filter( 'posts_where', 'filter_where' );
while ($query->have_posts()) {
$the_query->the_post();
echo '<li>' . get_the_title() . '</li>';
}

Unfortunately, the number seemed to bit off. To fit it, I used the idea in the following post (StackOverflow) to add in my argument, -1. Now, your same code should be similar to below:

//updated args
$args = array(
'posts_per_page' => -1,
'post_status' => 'publish'
);

Full source code:

<?php
define('WP_USE_THEMES', false);
require('/the/path/to/your/wp-blog-header.php'); //found in the root of your WordPress install.
switch_to_blog($blogID);
//updated args
$args = array(
'posts_per_page' => -1,
'post_status' => 'publish'
);
function filter_where( $where = '' ) {
// posts in the last 30 days
$where .= " AND post_date > '" . date('Y-m-d', strtotime('-30 days')) . "'"; //change 30 to the number of days you want
return $where;
}
add_filter( 'posts_where', 'filter_where' );
$query = new WP_Query( $args );
remove_filter( 'posts_where', 'filter_where' );

while ($query->have_posts()) {
$the_query->the_post();
if (get_the_title()<>''){
echo get_the_title().'<br />';
}
}
?>

Other Resources:

StackExchange post
Switch Blog in MultiSite