I had this problem also and it was caused because all of the files in the ws-includes folder did not upload when I moved them from my computer to the server. (This may happen if there is a stall in the internet connection during the upload.) In any case, I re-uploaded the ws-includes folder and my site popped back in.
I discovered this by reading the error message carefully. There was no "load.php" file in the ws-includes folder. That is how I realized all of the files didn't upload.
If you look at the error message it says "Failed opening required '/home/.../public_html/wp-includes/load.php". The first thing to do is to check to see if this file exists. If not, there's the problem. Also, when uploading files, it's good to do a visual inspection. Open each folder and see if the same amount of files are on your server that are on your local harddrive. This can also tell you if things uploaded correctly.
I have been helped by so many others on these forums that I thought I would throw in my two cents.