Error Establishing a Connection

I am trying to get to my site today and instead am getting the ‘error establishing a connection’ message. Same thing when I put the /wp-admin in the navbar. I haven’t changed anything in the config file and it worked fine when I was in admin on Sunday changing fonts in the CSS sheet. I didn’t touch anything anywhere else. How do I tell if the server is down or what do I do next? (Sorry, I know that sounds incredibly stupid but I haven’t yet run into this before.) Thanks!