First, check your PHP file with this code and then enable the fopen in your php.ini file
<?php
if( ini_get('allow_url_fopen') ) {
die('allow_url_fopen is enabled. file_get_contents should work well');
} else {
die('allow_url_fopen is disabled. file_get_contents would not work');
}
?>
Edit the php.ini file and enable using below code
allow_url_fopen = 1 //0 for Off and 1 for On Flag