Switching themes causes jQuery stops working properly

Switching themes causes jQuery stops working properly

Hey,

I hope this is the right place for this question.
I've created my website and design with the smoothness theme, and have used the standard jQuery scripts for creating buttons, menus etc.

I wanted to change to a new theme, and thus I went an downloaded through the theme roller new themes.
I added those themes to the css folder of my site and unfortunately the theme does get picked up, but the jQuery standard scripts stopped working.
The only change I've made in my theme choosing is this:

  <link rel="stylesheet" href="css/smoothness/jquery-ui-1.10.4.custom.css">

was changed to:
     <link rel="stylesheet" href="css/ui-darkness/jquery-ui-1.10.4.custom.css">

Now all the buttons and menus appear as bullets, and not as if they should be. At least the font/color is from the theme..

No error on the console or anywhere..

Any idea on how to solve this?