403/404 errors

Hello,

I am having issues with my website that seemed to happen out of nowhere (it was working perfectly fine as of Tuesday afternoon. When users try to access the site they get a:

Forbidden
You don’t have permission to access this resource.

Additionally, a 403 Forbidden error was encountered while trying to use an ErrorDocument to handle the request.

When I try to access the site editor I get a:
Not Found
The requested URL was not found on this server.

Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.

I’m not quite sure how to get back into my website and fix things. I’ve been editing the site from my chrome browser, but just downloaded wordpress to my chromebook to try and get around this. When it asked me to put in my website I get the following message:
couldn’t connect we received a 403 error when trying to access your site XMLRPC endpoint

Thank you for any help anyone can provide. I’m a complete novice when it comes to almost all of this and I took over for a the guy that set it up and everything but has since passed away. I’ve been handling the site for almost 6 months now and everything had been going great up until this.

The page I need help with: [log in to see the link]