Custom Post Type doesn’t use single.php or single-{custom_post_type}.php

First Didn’t did you create custom post type page?

Example i have a custom post type called compute i will create a file called compute.php and single-compute.php and write your code for multiple posts in compute.php and single post in single-compute.php if you still not showing or showing file not found try to logout your site and delete browser history and open in another browser try to login hope this would help 🙂