You need to download standard template (not quickstart, not rest_files) package.
When replacing current template, all changes made to previous will be lost - have that in mind, and if You have made some changes to override.css or any other files - copy them first, and then basing on them, reverse those changes to updated template files.
If it goes to slideshow - without any further information I cant guarantee You, that it will work with new template. I would need to know what slideshow, is it our plugin, or some 3rd party plugin, link to side and info where this slideshow should be would be halpful also.