Contribute CS5 won't let me connect to the server & says my password and username is incorrect.

I have had this program for along time now and never had any problems until recently. Now, whenever I try to connect to one of my wesites it prompts me for my username and password. So I type in my username and password and it says that one of them is incorrect. I haven't changed my username or password so I don't understand why it is saying this and won't let me connect. Sometimes it also pops up that it can't connect to the network server and that I need to contact an administrator. This is very frustrating because I have tried everything I can think of to fix this problem. It has been like this for a couple weeks now and I really need to get on my wesite, so if you know how to fix this please let me know. I need help asap! Thank you.