only error dispalying on my website and I cannot logging into my dashboard

yesterdat night I installed ithemes security plugin and configure some settings. After that, now opened my website and tried to loginto my website it shows error only in the both sections i.e on website and login dashboard. please help in solving?

Please send me a screenshot and your configuration.
And what do you mean by “plugin”?

And more importantly: what do you mean by error? What kind of error do you see? What does it say?