pagination not working on custom template

Hello there!

I’m working on a website were I used selfmade templates. There are some templates on which I include a category. So, the posts are being loaded in a page.

The problem I have is that no kind of pagination or standard navigation (next & previous post) is working. Not even something like this:

<?php global $wp_query, $meta ,$paged;
$page = (get_query_var('paged')) ? get_query_var('paged') : 1;
$temp = $wp_query;
$wp_query= null;
$wp_query = new WP_Query();
$wp_query->query("paged=$page&cat=3");
if(function_exists('wp_pagenavi')) { wp_pagenavi(); }
while ($wp_query->have_posts()) : $wp_query->the_post();
?>
<?php endwhile ?>
<?php if(function_exists('wp_pagenavi')) { wp_pagenavi(); } ?>
<?php $wp_query = null; $wp_query = $temp; ?>

[Please post code or markup snippets between backticks or use the code button.]

Does anybody know how to solve this?

Thanks in advance!