The slideshow has probably stopped working because of some JavaScript errors that are showing on your page. You can see these errors by opening the Google Chrome browser, right-clicking on ‘Inspect element’. You’ll then be able to view the errors in the ‘Console’ tab.
You can see whether or not the administrator has the correct rights to edit a slideshow using the Members plugin. If the rights are set incorrectly, it’s likely that another plugin is interfering with the slideshow’s user rights.