Thank you very much Greenreader9 for your quick response, it’s very kind of you!
I’ve just disabled Avast Antivirus and it works again.
I am very curious to know why this antivirus suddenly blocked my access to the site, without having changed his settings.
Something must not fit with AA in my html code.
Antivirus programs make mistakes sometimes. There might be something about the way your site is made, programmed, behaves or looks that Avast thinks seems suspicious. Fortunately you can submit it to Avast as being a false positive from this form: Report False Positive
In the meantime, you can follow these directions for Avast to exclude scanning the URL of your website, so you at least can access it.
I can’t read the screenshot unfortunately, can you translate it to English?
As for the reason why, it could be content on your site, bad neighbor effect, or something else. Only way to know for sure is ask the company that blocked it.