"Test it now" button opens "Page Not Found" error

By: sandee*** On: Sat Feb 18 18:38:31 IST 2017     0 0 0	0
i m trying to practice from ur site, from 16th feb 2017 onwards ur website is not working. while clicking on Test_it_now button Page_Not_Found error is showing. Please sort out this kind of problem it will help me. waiting for ur reply.!!!	0