If you are facing the IISPassword Error like follow:
IISPassword The page cannot be displayed
in your website, installed locally or on any website / domain, then this is probably the issue that your server has been installed on Windows Server, and there will be a .htaccess file existing in your root or some other folder, where your webpage exists.
How To Remove IISPassword Error
For removing this error from your website, simply access your web folder, and delete the (hidden) .htaccess file from your web folder. For example, if you are getting this error on a domain say http://www.webtechquery.com, then the .htaccess file should be existing in the root folder. Or if you are accessing a webpage existing in your folder inside root or somewhere else, then the .htaccess file should be existing in that folder.
Simply remove the .htaccess file through your ftp or any other resource, and your problem will be solved.
Remove FTP Files Through FireFTP
For removing the file through FTP, you can use Firefox addon FireFTP, which could be easy for you to manage your FTP files like delete, upload or download your files existing in your domain or website, without any use of FTP software.
However, if you want to use the .htaccess file, then it is preferable to install your website or domains on Linux Server instead of Windows Server.