Update failed and worse

So I noticed this morning when I logged into Dashboard that there was an update available to 4.2.1. I clicked to do it without backing up, and it froze. Now, my URL is nonresponsive, I cannot access the dashboard, and I’m a real neophyte when it comes to code. I have maintained the website for 4 years just using the dashboard, and I have no idea what to do.

I can access the files via ftp, but I don’t know what I should be trying to see/replace/rename.

Any help would be very much appreciated.

The URL is acatribe.com, though you won’t see anything there. 🙁