Connection Refused: Connect on Minecraft Server? - 2

Okay, I'd like to start off by saying I'm kind of new to this whole server thing - but I've been able to play Minecraft on my friend's server for several weeks without a problem, using update 1.6.4 (since that was the only one that worked). Suddenly though, it keeps saying Connection Refused: Connect. How do I fix this?

Added (1). I have restarted minecraft multiple times and i don't know how to join another server. I only have the one server

It can be fixed multiple ways but two easy ones are:
1) Join another server for a couple minutes, then disconnect and reconnect to the server you want to join that has the error.
2) Restart Minecraft

Here you may get some help
http://bestwebpost.weebly.com

Does the server show up in your server list with green bars? If it shows up with a red X either someone needs to restart the server or maybe its IP address changed (especially if a home server with dynamic public IP).