#2 Error I can't see the site

[Anonymous]

Hi I need help!! please!
I was posting an article, as usual. When I clicked Ok to upload it,
the following message appeared:

Unable to load the data file.
Reason: An invalid character was found in text content.
Line: 9390
Line Pos: 801

Now I can no longer access anything in the web site, the web
page, or on the administration site.

I'm not a developer so I do not understand what is it about. Could
somebody give me a hand.

I will appreciate it very much!