Make jQuery library load before plugin files in child theme

I'm setting up a site with child theme. I have installed several plugins. But few plugin files (fancybox, jQuery UI files) are loading before the jQuery library. So I am getting this error: undefined is not a function.

How can I load the jQuery library before any other .js files. Note that I only have access to functions.php of child theme and there is no wp_enqueue_script function in that file.

Can anyone help me how to do this?