If you click on this link... If LW Will Not Connect
... you'll find instructions for finding the gnutella.net file. If deleting that file & then restarting LW doesn't help, that link has more links where you can download a new gnutella.net file. There are instructions for replacing the gnutella.net file.

Make sure that your XP firewall is allowing LW (click on link): PortForward.com - Free Help Setting up Your Windows XP Firewall.

After you deleted LW's preferences folder, did you have to go through LW's setup wizard all over again?

Did you try all of the other fixes in the help thread?

Did you remember to click Apply after changing port numbers? Also, try a few different numbers in the range shown in the 'if LW will not connect' thread. If the port 6346 test doesn't work, it can sometimes mean that an ISP is blocking some ports.

You can also try port forwarding, rather than using UPnP. The instructions are here: Port Forwarding for the Netgear WGT624v3
First, you'll need to set up a static IP address: PortForward.com - Free Help Setting up Your Router or Firewall
LW's listening port, port in the 'manual port forward' box & port forwarded within router config all have to be the same number