Only home and posts load.

Hello guys,

I’ve been working on a blog, adding stuff and just working on it.Today I wanted to access my admin cpanel but it wouldn’t load, I tried using the toolbar(from top of page), clicked on Add New, Dashboard, etc.It just won’t load the page.
Firefox says the page is loaded but all I see is an white screen, I can only load posts and the homepage.
I’ve never heard of such a problem, what could be the cause of it?

Thanks in advance,
Alex.