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 was also facing same problem but i renamed contact-form-7 plugin from /wp-content/plugins directory to contact-form-7-rename and problem solved.

So this is due to unsupportable plugins or theme.