if you use a windows hosting: You have to allow files without an extension, because Letsencrypt wants such a file.
Create the directory
/.well-known/acme-challenge/
and put a file with a name like 123456789 (no extension, content "test" or something else).
Test, if you can load
http://www.supremetechnologiesindia.com/.well-known/acme-challenge/123456789
in your browser.
If this doesn't work: An older post with the configuration: