PLEASE HELP homepage, login, everything is blank and white

I am freaking out. I was at my dashboard and next thing i know the page is white. If i tried to log in on a different browser the log in page is just white. anyhting i click on is white. The only way i see my dashboard is if i hit the back button, and even then when i click on something, anything plugins, comments, posts, anyhting it brings me to a blank page. im so confused please help!!!