How to enable PHP file_get_contents() function and PHP symlink() function?

You are not providing enough information here to really give you a comprehensive answer.

Are you using external URLs in file_get_contents()? If so you need to ensure that you have allow_url_fopen enabled in your php.ini.

Ref: https://www.php.net/manual/en/function.file-get-contents.php

For symlink(), tell us what error you get when you try to call it. Some common reasons for failure are:

1. No permissions to the file-system for the user under which PHP is executing
2. The symlink already exists
3. The target does not exist