Notmally the directory that there is no index.xxx file, we can list it as below

for example in fawasblog.com/IMG

solution to solve it is very simple,

1. Create new file ' .htaccess ' (including DOT) in your root directory of your website (beside of your index file)

2. write the command Options -Indexes

3. Save and upload to your hosting

lets play again to fawasblog.com/IMG 

now you are forbid to list the directory, and every directory too!