I will suggest you to try inbuilt utilities in vista to recover your music files, I am not sure that it will recover them. But if you are still unable to recover them then you need data recovery software. Once I faced same situation when due to virus attack I lost my all music files, it was the collection of 5 years. I used Stellar Phoenix Windows Data Recovery from here:
Partition Recovery Software, provides partition recovery for lost Windows partition of FAT & NTFS partition , it also recover music files. I used demo version first and after using it I was very happy to see my all music files. I purchased the full version and saved my music files.