Hope page not coming up

As of yesterday, my homepage is not coming up. It is blank! When I tried to do a work around by puting in"wp-register.php" and wp-login.php" after the root, I got this error message:

Warning: require(/home/content/l/e/s/lesbionix/html/wp-includes/compat.php) [function.require]: failed to open stream: No such file or directory in /home/content/l/e/s/lesbionix/html/wp-settings.php on line 246

I didn't change anything and don't have the slightest idea as to what has happened. Any help would be greatly appreciated. I am using version 1.5, I think.