dfi_get_featured_images not working

Hi, I had installed the plugin and it was working all well and I just noticed that it is not working now, I get this error message:
Fatal error: Call to undefined function dfi_get_featured_images() in /home/content/78/5453678/html/thecompasswithin/blog/wp-content/themes/custom/index.php on line 22

http://thecompasswithin.com/

Thanks for the help!

https://wordpress.org/plugins/dynamic-featured-image/