Blank screen in Wordpress admin. Please help.

Okay, I just went into my wordpress account for a site I am building, and whenever I try to either add a page, add a post, or edit a page or post, I am being taken to post.php and it is a blank screen! I don't know what happened, because last time I was editing the site, it was working just fine.

If anyone has had a similar issue, please let me know as soon as you can.