Access to FTP was removed from Mountain Lion, but the service itself still lives on - it's just a matter of getting access to it.
I found an article that talks about a third-party script that was written to get you access:
Hope this helps!
If you have upgraded to Mountain Lion from Lion, then it basically uninstalled any server software you had before. You will need to download and install the 10.8 server to get the server functionality. Once you have the application "Server" installed on your computer, Mountain Lion server will import any settings including users and such that were in your 10.7 Lion server.
Also, if you didn't download server and install it ever, you probably don't have a server. As far as I know, the mac mini "server" still comes with the client OS and you have to download the server upgrade and install it over the client base OS.
*Be ware however, I have now performed 3 and my company has done about 6 upgrades from 10.7 to 10.8 and Mountain Lion sometimes messes up permissions on shares from previous versoins of the server. Be sure that each user can still log in and get access to any shares after upgrading.