Hi, there could be many reasons I suppose.
Has the ftp login data been accidentally changed? Is there a new firewall on the PC that blocks ED's access to the internet? Have the ED program files damaged?
There could be a zillion reasons for this., but if the ftp-server can be accessed by another program, you can be sure the server itself is working fine.
Start by checking the ftp settings in ED! Check firewall settings. Try reinstalling ED again.
Impossible to help more without more detailed info.
Cheers,
Erasmus