NEED HELP!!! Connection closes automatically after I connect

Everything has been working great until today. Everytime I open FTP and connect it, it goes through the usual list - NOTHING IS DIFFERENT - but then it automatically says "connection closed" and the connection is closed. It's as if I closed the connection. What is going on?? It is not my server, I can publish my project through them no problem, but I cannot do anything with FTP.
Please please help!!
I already tried to restore my computer, installed stuff, etc. and nothing has changed. Help!!!!