My site http://wizardspost.com/ is WORKING but a strange problem has appeared.
I was UPGRADING to wordpress latest version when it stalled ( I think) On refreshing it gave the following messages:
Warning: call_user_func_array() [function.call-user-func-array]: First argument is expected to be a valid callback, '__return_zero' was given in /home/wizard/public_html/wordpress/wp-includes/plugin.php on line 166
Fatal error: Call to undefined function is_multisite() in /home/wizard/public_html/wordpress/wp-login.php on line 85
Now I cannot login to my wp-admin.
Can anyone suggest what I should do.