Need your help for this error i have search also wordpress Forms but not find out perfect solution for that

Even not given permission of wp-admin.
Fatal Error: Call to undefined function wp_get_current_user() in /wp-includes/class-wp.php Line no.529


Please No One Have Solution For that.

Well, that sounds like there is no easy solution. You'd just have to find out what wp_get_current_user() does, where it comes from, when it should be included and why it isn't included in your file. Or find someone with the same problem, but it doesn't really sound like a much occurring problem ;p.