Trouble Adding Media

I used to add photos to my pages and posts with no problem. Now when I click the Upload an image button, nothing pops up and my page stays the same. I can add an image by writing the code myself, but I’m not sure why I the button no longer works. Any help would be appreciated. I recently changed my theme to Atahualpa. Not sure if the timing is the same, but could that be it? Anyone know how to fix?
Thanks in advance.