Have you tried reaching out to the author about this issue? Since your website’s functionality relies on your server, problems could arise from a missing PHP extension, a MySQL database issue, or server misconfiguration. The author might be able to help you identify and resolve the problem. You can contact them through their support page: https://support.digisamaritan.com/.
If the issue remains unresolved, you can request a refund via http://themeforest.net/refund_requests/new.