Web page not available

Hi all
I am not very technically minded, but have a web page which a friend helped me set up on WordPress. Unfortunately I can’t contact him at the moment.

The web page won’t open and I get a message saying “This web page is not available”. I accessed it last on Monday, and it was working ok then; but since then no-one has been able to access it.

Any advice on what to do, in beginners’s steps please, would be gratefully received. The only thing that happened on Monday was that the font had changed and I changed it back. I was using a font add-on, but I can’t tell you which one as I can’t access my dashboard either.

I am running Chrome on a Windows 8 machine. Please do let me know what other info will help.