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

In my case, wp-admin/post.php blank screen was fixed by removing the " ?> " at the end of my function.php in my child theme. I don't know how the end tag ended in there, but removing it solved my problems.