Unable to login to wp-admin page 404 not found error

I have a website https://www.kyonnikala.com ,which was working fine since 2 months .Today when i try to access my website is showing error 404 not found and showing only website name and page .when i click on any page it shows not found . when i try to login my wp-admin page it shows error message

“The requested URL /wp-login.php was not found on this server.
Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request. ”

Please suggest me the possible solution .thanks

The page I need help with: [log in to see the link]