A lot of WordPress themes these days make use of java-script/jQuery to enhance the themes adding things such as image sliders, toggles, accordions, tabs, mobile menus, image hovers…etc.
If the these features are not working on your theme or suddenly stopped working its most likely do to some sort of javascript error causing everything to break.
Broken Slides, Toggles, Tabs, etc Error Solution
The first thing you should do is disable all your plugins, clear your cache (all of them) and re-load your site to check if everything is working how it should be. If it is, then now you can activate your plugins back 1 by 1 and as soon as it breaks you’ll know that last plugin was the one causing issues (make note of this plugin, deactivate then keep doing the same).
Once you know which plugin/plugins are causing the issue you can either search for new plugin with the same functionality that is compatible, or you can contact the plugin or theme developer to let them know of the conflict (first inspect the page to see what the actual issues are so you can contact the appropriate person – if its a plugin error send a note the plugin dev, or if its a theme error the theme dev).