If you're sure you're not seeing fake files,
Fake files showing up in search results
and if absolutely everything you try to download gives you the connecting/need more sources message, delete your preferences folder when LW's properly closed.

See point 3 below (also point 2 if you've used much older versions of LW in the past).
Fixes for LimeWire
This will kill all of your settings within options, you'll have to go back through later & reset things to the way you like them.