Search Just a Custom Post Type

cpt-search.php

<?php /*

	Search just a custom post type using WordPress' native search. 
	Uses Boostrap classes.
	
	Swap out "CustomPostTypeHere" for your custom post type slug.

*/ ?>

<form class="form-inline" action="<?php echo home_url( '/' ); ?>">
	<div class="form-group mx-sm-3 mb-2">
		<label for="cptsearch" class="sr-only">Search</label>
		<input type="search" class="form-control" id="cptsearch" name="s" placeholder="Search">
	</div>
	<input type="hidden" name="post_type" value="CustomPostTypeHere">
	<button type="submit" class="btn btn-primary mb-2">Search</button>
</form>