WordPress white screen of death

Hi all

My business website has completely vanished… I’ve turned on debug, and I’m getting the following error:

Notice: Undefined index: t9d038 in /home/cluster-sites/4/b/businessfiction.co.uk/public_html/wp-includes/class-wp-tax-query.php on line 1 Warning: require_once(/home/cluster-sites/4/b/businessfiction.co.uk/public_html/wp-includes/widgets/class-wp-widget-categories.php): failed to open stream: No such file or directory in /home/cluster-sites/4/b/businessfiction.co.uk/public_html/wp-includes/default-widgets.php on line 32 Fatal error: require_once(): Failed opening required ‘/home/cluster-sites/4/b/businessfiction.co.uk/public_html/wp-includes/widgets/class-wp-widget-categories.php’ (include_path=’.:/usr/share/pear54:/usr/share/php’) in /home/cluster-sites/4/b/businessfiction.co.uk/public_html/wp-includes/default-widgets.php on line 32

Any help offered will be hugely appreciated.

Website is: https://www.businessfiction.co.uk