Broken media gallery; jQuery likely to blame

After having a number of issues getting a theme which called up an outdated version of jQuery, which conflicted with certain plug-ins and caused the slider on my mainpage to stop working, I have solved the issue with the slider but run into another one completely.

Now, whenever I attempt to go to media gallery, it will not open. I can open it in a new tab, but the “show” link does absolutely nothing so I cannot edit the images in any way. I am assuming this has something to do with this code, which solved my slider problem:

wp_deregister_script('jquery');
wp_register_script('jquery', ("https://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js"), false, '1.4.2', false);
wp_enqueue_script('jquery');

My mainpage is located at dehydrogenated.net if anyone cares to take a look there, but either way any advice and I’d be extremely grateful!