The default location for your shared folder is C:\Documents and Settings\"your account name"\Shared. If not there, try searching your harddrive(hdd). I'm assuming your using windows. From your desktop go to Start>Search, and search for the title of one of your files. If it's still on your hdd it'll show up in the search and you'll find the folder they're in.
If they're not there, you'll need a file recovery program to get them back. See
DELETING FILES FROM LIMEWIRE LIBRARY-DON"T! - File recovery advice!.
You could also try deleting the LW Preferences folder called limewire (whilst LW is closed!). Instructions in this thread:
Fixes for Limewire when LW isn't operating as it should!
Let us know how you get on.