How to display search form in WordPress theme

First you need to check if the file searchform.php exists in the root of the site theme.

The content of this file should be like this:

<form role="search" method="get" id="searchform" action="<?php echo home_url( '/' ) ?>" >
	<label class="screen-reader-text" for="s">Search: </label>
	<input type="text" value="<?php echo get_search_query() ?>" name="s" id="s" />
	<input type="submit" id="searchsubmit" value="search" />
</form>

In value=”search” you can add any text for the search button. If the file searchform.php does not exist, then just create it and copy-paste the content from the example above.

To display the form anywhere in your wp theme, use the get_search_form function:

<?php get_search_form(); ?>