Try the fixes in the thread below, there are lots to try.
If LW Will Not Connect

You might not have a .limewire folder, if you're using a later version of LW. Read the 'delete preferences folder' bit in that help thread for more info.

You need to make sure that you're looking in the right place for the gnutella.net file...check the help thread for basic instructions.

If nothing there helps, post back with your system details...see the help thread for info about which details we need.