[Plugin: DISQUS Comment System] does not work anymore

Hi people,
I have a critical problem with DISQUS Comment System on my blog. In a few words, some weeks ago the plugin stopped to work suddenly and without any apparent reason. I already tried to uninstall it and after that to install it again but this procedure didn’t work. Now I can’t loggin to DISQUS Comment System from wp admin panel, moreover I receive the following error:

Disqus Comments has not yet been configured. (Click here to configure)

Unexpected error.

I’m posting also an image https://img18.imageshack.us/i/disqus.jpg/
If I can’t loggin it’s not possible to manage the comments in my blog. Please, help me, I really don’t know what I’m supposed to do.
Thanks