In LW file > disconnect. Wait 5 minutes then file > connect.

Delete LW's preferences folder when LW's properly closed. See point 3 here & also point 2 if you've used older versions of LW in the past (there could be a folder in either location).
Fixes for LimeWire
This will change all of your settings within options, you'll have to go back through afterwards & reset things. If you're not sure of your settings, go through LW's tools > options & write them all down, so that you can reset things later.

Are you using the same version of Java now as you were when LW was connecting?

You could try port forwarding for your router. These instructions are for the DI655, have a look & see whether the instructions suit your model.
Port Forwarding for the Dlink DIR-655
You'll need to set up a static IP address first, or port forwarding won't work. LW's listening port, port in the 'manual port forward' box & port forwarded within the router should all be the same number.