Did you replace the gnutella.net file (within LW's preferences folder named LimeWire)?

Do you use a modem or router? Look for a box with lights on it which connects to your computer & lets you connect to the net. If you're using a wireless connection, the modem/router might be in another room.

In LW go tools > options > advanced > firewall config. Change LW's listening port to 64049 > apply > ok. You can also try other ports in the range of 49152 - 65535.

If you can find your model in the list here, try port forwarding.
PortForward.com - Free Help Setting up Your Router or Firewall
Click on your modem/router model & then choose LimeWire from the list of programs. Then you'll see step-by-step instructions for port forwarding.

If setting up a static IP is part of the instructions, don't miss that step. LW's listening port, port in the 'manual port forward' box & port forwarded within the router setup should all be the same number