wendyx there's different methods to search. When searching for songs, also try an Any Type search. Also try the song or artist or even slightly mispell the name as some people mis-label their files. So also try varying your search criteria to help with your searches.
You seem to have a major issue though if you're not getting any search results. If you're a windows user, delete your LW preferences folder whilst LW is closed as directed here:
Fixes for Limewire That will probably fix your problem. If not post back & give us some details about who your isp provider is & what equipment you're using.