Sorry Tony, you;re missing the second part: "and update your server rewrite rules to use wp-includes/ms-files.php instead"
If you do not do this all your uploaded images will disappear.
AlexV - in Cpanel, when you first go to the file manager, check the box to show hidden files. In the same root where the wp-config.php file is (usually public_html) there's a file called .htaccess. It has the dot in front, that means it's usually hidden. This is where the rewrite rules are.
RewriteRule ^(.*/)?files/(.*) wp-content/blogs.php?file=$2 [L]
Change it to:
RewriteRule ^(.*/)?files/(.*) wp-includes/ms-files.php?file=$2 [L]
Deleting the old blogs.php file doesn't even matter if you change the rewrite rules first.