Sliding Door Menu

My client “broke” the theme after WP update to 4.4.2. I backed up the history and got the site back up, but the sliding door is the default images and links again. I put this site up several years ago, and altered the links in the function.php file. Trying NOT to do that again, because I don’t want to go through this again. Where do you change the images and the links for the menu in this theme? I saw the customize menu, and I can do that, but how do you change the images?