The error 404 displays in a browser upon trying a URL with valid domain name, but simply cannot provide you the access to the resources specified in URL. It means the domain is valid but the page you have tried to access is invalid, don’t exist anymore, deleted from server or being moved permanently.
The other possibility is that the particular server might hosted the file but now it is being moved to another computer, but it does not or cannot provide redirection to the other computer which is hosting the site now. If it happens in result of a redirect, make it sure that the root directory of the server is being correctly configured with the software doing redirects. Make sure that you haven’t mistyped or misspelled the URL. Contact support and technical department if you need further help.