致命错误：在第28行的wp-includes / query.php中调用非对象的成员函数get（）

I have my own Wordpress site and one day when I tried to add new post I couldn't sign in and it said this

Fatal error:

Call to a member function get() on a non-object in /home3/accountName/public_html/wp-includes/query.php on line 28

PLz help me !