My website has gone! (Noob weeping)

I just tried to go onto my site at harrietbedford.com but it’s down and all I get are 404 errors.

I can’t get into my WP dashboard or cPanel either. Everything seems to have broken at once and I have no idea why.

I am embarrassingly noob at all of this. I don’t have a clue where to start but I need it back up asap for my business.

White knights/knightesses required! HELP!!!