Do you mean that you get no search results, or that nothing show up in the download pane (where you see the list of files you're downloading)?

If you see no search results, try this: Problems with the search

And if that's no help, 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 kill all of your settings within options, you'll have to go back through afterwards & reset things.

If neither of those help, please give us your details.
System details - help us to help you (click here)
Is your connection to the network ok? How many green bars do you see?


If you see search results, but nothing shows up in the download pane, try this: License (click)