Help...Cant upload site and cant determine why

I have had my site up and running and after making some changes I cant seem to up load it any longer.
Here are the settings I have on my web design software,
Port 21
User jason6
When I test the connection with the server it connects and when i do the upload the information is going somewhere but the site itself comes up with this error:
Not Found

The requested URL / was not found on this server.

Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.

Any help would be appreciated.

If you didn’t do anything silly like click ‘remove’ under webhosting on the manage domains page, then you might want to contact support via the webpanel, it’s possible the domain was disabled for some reason.