I can't update/edit anything. 403 error pops up

Hello,

I can’t update anything on my WordPress site (Stylings & Stories). When I click “update file” in the editor, custom css, posts, pages, everywhere, a 403 error page pops up and updates cannot be made.

The error started happening after I tried updating my page.php file to have custom headers for each page.

This is the code that I used. (I used a modified version of this for my purposes) ::

<?php
if ( is_home() ) :
	get_header( 'home' );
elseif ( is_404() ) :
	get_header( '404' );
else :
	get_header();
endif;
?>

Which I got from here ::

So my page.php file looked like this ::

<?php
/**
 * Page Template
 *
 * This is the default page template.  It is used when a more specific template can't be found to display
 * singular views of pages.
 *
 * @package Origin
 * @subpackage Template
 */

if ( is_mini-masterclass() ) :
	get_header( 'mini-masterclass' );
else :
	get_header();
endif;
?>

	<?php do_atomic( 'before_content' ); // origin_before_content ?>

	<div id="content">...

After I made this update is when everything went wrong. Now this update that I made doesn’t even show in my page.php file.

Things I have tried ::

• Re-uploading the original page.php file
• Switching themes
• Uninstalling + re-installing my current theme
• Changing the .htaccess file

The .htaccess code I used is this ::

It sounds like you may be hitting a mod_security error.  Add the following to .htaccess:

<IfModule mod_security.c>
SecFilterEngine Off
SecFilterScanPOST Off
</IfModule>

which I got from here ::

Please help!
Thank you,
Stephanie