website disappeared

Hi, I have a WordPress website however it has disappeared !! when I try ti find it via google or try to access the WP admin I get the following message:

Fatal error: Class ‘Kirki’ not found in /home4/nburgess/public_html/wp-content/themes/evolve/inc/admin/customizer/customizer.php on line 1217

Can anybody help ?!!

Thankyou

The page I need help with: [log in to see the link]