Where to begin reloading music lost

[Nitecat]

My hard drive has bit the dust. I had previously been able to get 38 gig of my songs backed up, but was never able to get the rest done (no lectures please). I had a total of 53 gigs of songs, so have lost 15 gig and will need to reload them. My only other option at this point is to find someone who can try data recovery/clean room, but I assume that would be very expensive. I have song books already made up with the 53 gigs of songs and need the Book Ids to remain as previously loaded. With the news (wonderful Christmas present) from my electronic repair shop that they have found no way to retrieve the data, I am presented with determining what music I'm missing and how to go about reloading the 15 gigs of music that was lost. Figuring out what is missing....hhhmmm, not sure how to do this either. Also, do I point to the new drive that has the 38 gigs that are OK and rebuild the database, then reload the 15 gigs of lost music, making sure to load with the same book ID used before? I'm feeling a bit confused, so any advice would be appreciated. Not sure if this will work or if I'm missing something. Help!