why does not my wp_query work?

Question

There are several issues here, starting with the first part:

<?php 
    $postnumcat = new wp_query (array(
    'post_status' => 'publish',
    'post_type' => 'post',
    'cat' => '-1',
    'posts_per_page' => '-1',
    ));

Firstly, wp_query is misspelt, it’s WP_Query

Some general notes too:

Setting posts_per_page to -1 is bad for performance. Even if you don’t expect there to be many posts, set a super high number instead, but never say -1 as that means unlimited, even if your server can’t handle it. Use pagination if there are too many results
Setting cat to -1 tells WP to exclude the category with the term -1, which can be extremely slow and expensive. Avoid these kinds of queries at all costs

Then for some reason, there’s a closing PHP tag, a space and newline, then an opening PHP tag, this will create unwanted whitespace:

?>

<?php if($postnumcat->have_posts()) :

Then we have the loop, which hasn’t been formatted correctly, but notice there is nothing inside the loop, all you’re going to get is a series of . The code needs to actually display things

while($postnumcat->have_posts()) : $postnumcat->the_post(); ?>

<!-- Loop elements -->

<?php endwhile; endif; wp_reset_query(); ?>

And finally, wp_reset_query is for use with query_posts, a function you should never use. Black list wp_reset_query and never use it, there is no reason for you to use it.

Instead, lets go back to the original task:

i want to display archive of posts for post type of post. so i created a page template and insert the following codes but i display nothing. why? what should i do?

WordPress already does this! By default this is your homepage ( home.php/archive.php/index.php ). But if you wanted to put this archive on a different page, using a page template then throwing away the main query and using your own is a terrible way to do it.

Imagine you sent your assistant off to buy you a coffee every morning. Except after she came back from a 40 minute round trip, you told them “No, I want a Hot Chocolate”. Every morning you make them go out twice. Then the client complains your business is slow and doesn’t perform well.

On top of that, you’ve just lost a lot of the benefits of WP, e.g. pagination will break, and you’ll need to re-implement it to get it working again.

Instead, create a page called “Post Archive”, go into settings, and under reading, set it as your posts page:

Then, create a frontpage.php and a home.php in your theme so that you can style them both. Use a normal, standard, main post loop in both.

For reference

This is a standard main loop:

if ( have_posts() ) {
    while ( have_posts() ) {
        the_post();
        the_title();
        the_content();
    }
} else {
    // no posts found
}

This is a custom post query:

$q = new WP_Query( [
    // args go here
]);
if ( $q->have_posts() ) {
    while ( $q->have_posts() ) {
        $q->the_post();
        the_title();
        the_content();
    }
    wp_reset_postdata();
} else {
    // no posts found
}

And this is what you’re supposed to do if you want to modify which posts WordPress fetches, by telling it before it fetches them:

function my_home_category( $query ) {
    if ( $query->is_home() && $query->is_main_query() ) {
        // only show posts from category 123 on the homepage
        $query->set( 'cat', '123' );
    }
}
add_action( 'pre_get_posts', 'my_home_category' );

And finally, put each thing on its own line, and indent them. There are a lot of free editors that will automatically do this for you, e.g. Sublime Text, VS Code, Atom, etc

For reference

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