not very sure
 

Okay, my limewire was working fine yesterday, and i just get on now and i Start up limewire 4.12.3, and it goes past the loading screen and stuff, but nothing comes up. i did the same thing again and let it sit for an hour, and STILL, nothing will come up, and it was working fine yesterday and this morning

Remove your old Java version & reinstall using the offline installer here
http://www.java.com/en/download/manual.jsp

If that doesn't fix things, try deleting the preferences folder (points 2 & 3 here) when LW is closed
Fixes for LimeWire
(this will kill your settings within tools > options. You'll have to go back & reset everything afterwards)

If still no joy, reinstall LW using it's offline installer here
http://www.limewire.com/english/content/download.shtml
:)