Your music should still be there, deleting the preference folder has never caused music to be deleted before...
Try these suggestions and see if they help...
Try uninstalling all versions of Java from the add/remove programs and then use
Crap Cleaner to clean the registry.
Try updating to the latest version of Java here
Java SE Downloads
If the latest update gives you any problems, try this older version, which has worked well for lots of people:
Archive: Download Java 2 Platform Standard Edition (J2SE) 5.0 Update 11 Whichever Java version you use, download the JRE offline installer & remove any other Java versions (via Add/Remove Programs) before installing another one.
If none of the above fix your problem you will need to start fresh using the offline installers for both Limewire and Java...
Limewire offline installer:
http://www9.limewire.com/download/LimeWireWin-full.exe