Theme no longer supported and not working on WP 4.1.1

Hi. I built a client’s website on Fotofolia Landscape and suddendly it’s stopped working. The site just won’t load. I tested it by activating one of the WP themes and it was fine again, so I know it’s theme related. My problem is that the developers are gone and with them, so is the support. Is there a way I can make the theme work with the new version of WP (at least until I can rebuild it on a different theme)?