Limewire stopped working for me one day just out of the blue. It drove me mad, I downloaded Frostwire instead and had no issues, connected fine, but I wanted my Limewire. I tried so many things to get Limewire reconnected, messed with settings in my router, uninstalled, reinstalled, nothing. I just went the this site (from a link in the forums here) and found my antivirus program in the list, I followed the directions for port forwarding exactly, I now have a full connection! Give it a try, can't hurt.

PortForward.com - Free Help Setting up Your Router or Firewall