If I remember rightly, from version 2.3 Limewire puts the shared and incomplete folders inside the preferences folder by default. You need to tell Limewire to use your old shared folder:

1. In Limewire, go to the Tools menu and select Options

2. The options window will open, select Sharing (2nd from top)

3. Click on Add and find your original Shared folder in the browser that appears.

4. Click on Select, then OK

That's it. Limewire should now display all your old files.