wp-admin shows blank page, how to fix it?

Question

I am working with WordPress 3.5.8. Yesterday I made some changes into it to a friend. I don\'t know what happened, but after some time when I try to log in at wp-admin side and

Answer 1

I found following solution working as I was using older version of wordpress.

1. Open file blog/wp-admin/includes/screen.php in your favorite text editor.
2. on line 706 find the following PHP statement: _help_sidebar; ?>
3. Replace it with the statement: _help_sidebar; ?>
4. Save your changes.