index.php showing code instead of page in PHP 7

[xH3LLRAIZ3Rx]

I am getting this issue where it shows the code of index.php instead of the actual page:
setupAutoloader($fileDir . '/library'); XenForo_Application::initialize($fileDir . '/library', $fileDir); XenForo_Application::set('page_start_time', $startTime); $fc = new XenForo_FrontController(new XenForo_Dependencies_Public()); $fc->run();

the home page of Xenporta 2 works, but any other tab does not, please help