WordPress loop is not working

custom-header.php

<!-- Start Top Header affix nav-->
<div id="affix" data-spy="affix" data-offset-top="94" data-offset-bottom="0">

<!-- **** START - NAVBAR SCROLLSPY FIX DO NOT REMOVE ****  --> 
<div id="top" class="hide"></div>
<!-- **** END - NAVBAR SCROLLSPY FIX DO NOT REMOVE **** -->

<!-- **** START - NAV **** -->
<nav class="navbar navbar-default navbar-shrink">
<div class="container">
<div class="navbar-header">
<!-- main-logo goes here-->
<h1 class="brand--font"><a href="https://wordpress.stackexchange.com/questions/150006/<?php echo esc_url( home_url("https://wordpress.stackexchange.com/" ) ); ?>">PRINTLABELANDMAIL.COM</a></h1>
    <button type="button" class="navbar-toggle" data-toggle="collapse" data-    target=".navbar-ex1-collapse">
      <span class="icon-menu"></span>
    </button>
            </div>
<!-- **** START - NAVBAR SCROLLSPY FIX DO NOT REMOVE **** -->
<li class="hide"><a href="#top"></a></li>
<!-- **** END - NAVBAR SCROLLSPY FIX DO NOT REMOVE **** -->
<?php

$defaults = array(
'theme_location'  => '',
'menu'            => 'main-nav',
'container_id'    => 'nav',
'container_class' => 'navbar navbar-default navbar-shrink',
'container'       => 'div',
'container_class' => 'collapse navbar-collapse navbar-ex1-collapse',
'container_id'    => '',
'menu_class'      => 'menu',
'menu_id'         => '',
'echo'            => true,
'fallback_cb'     => 'wp_page_menu',
'before'          => '',
'after'           => '',
'link_before'     => '',
'link_after'      => '',
'items_wrap'      => '<ul class="nav navbar-nav">%3$s</ul>',
'depth'           => 0,
'walker'          => ''
);

wp_nav_menu( $defaults );

?>
        </div>
    </nav><!-- **** END - NAV **** -->
</div><!-- **** END -affix NAV **** -->
<!-- end Top Header affix nav-->
<!-- **** start blog banner **** -->    
<div id="blog-banner">

<?php if (function_exists('dynamic_sidebar') && dynamic_sidebar('blog-banner')) :     else : ?>
<div class="pre-widget">
    <p><strong>Widgetized Area</strong></p>
    <p>This panel is active and ready for you to add some widgets via the WP  Admin</p>
</div>

<?php endif; ?>

</div>
<!-- **** / end blog banner **** -->    

content.php

<?php
/**
* The default template for displaying content.
*/
get_header('custom-header'); ?>
<!-- **** START - BLOG **** -->
<div class="container  blog">
  <div class="row  blog--row">
<!-- **** START - LEFT CONTENT -->
....
<!-- **** END - LEFT CONTENT **** -->
....

I would further recommend putting the sidebars in files named left-sidebar.php and right-sidebar.php, and your footer in custom-footer.php. The aim here is to separate layout from content.

The Ideal layout is:

• GetHeader
• GetSidebar(left) – optional
• Article Content
• Get Sidebar(right) – optional
• GetFooter

In that order. So that content.php only contains the article content, and the layout.

Welcome to WordPress.SE. Nice Design BTW…

1. get_header() Function Reference
2. get_footer() Function Reference
3. get_sidebar() Function Reference