connection failed!

Hello, sry for my terrible english!
I am a german user of WinSCP.
Yesterday the WinSCP works without any problems...
A few minutes ago i try to connect to my server via FTP.
suddenly WinSCP say's:

Es konnte keine Verbindung hergestellt werden, da der Zielcomputer die Verbindung verweigerte.
Connection failed.

In english it called (sry its a google translation):

It could not be contacted, because the destination computer refused the connection.

Why WinSCP works until yesterday correct, but today it isn't work!?
My root server operator says he could connect without any problem via WinSCP to my server. but i can't connect!
Any ideas? I didn't have changed any settings of my WinSCP.

Greetz Kasi

Thx for any help!

Please read documentation. If that does not help, come back.