Wordpress fix

I need a site fixed asap. Its a custom designed wordpress site. And now it tells me that the theme is broken. I get these errors: Warning: array_keys() expects parameter 1 to be array, boolean given in /home/monicspm/public_html/wp-includes/[login to view URL] on line 521 Warning: uksort() expects parameter 1 to be array, boolean given in /home/monicspm/public_html/wp-admin/includes/[login to view URL] on line 48 Warning: array_slice() expects parameter 1 to be array, boolean given in /home/monicspm/public_html/wp-admin/includes/[login to view URL] on line 55 It worked fine a few days ago, so its probably not a big issue, but since I know nothing about programming I need your help. Good english is a must.