working with wordpress 3.5.1

Hi, I am running wordpress 3.5.1 and I have tried to use the plugin but it keeps saying please wait and nothing happens.
I am waiting to hear back from my web developer to see if I can upgrade to the latest version of wordpress without breaking my site.
In the mean time is there something else I can do to make it work?
My site is http://www.christinefrancis.com

https://wordpress.org/plugins/wp-media-cleaner/