I got an email from my old boss. I found this useful.
A new one for me, if you had purchased music from Amazon since 1999, amazon now do a cloud search - which locates the music you purchased and can play online but also allows you to download a mp3 copy.
This lunch time I rediscovered 229 songs I had lost/mislaid
Simply login using your amazon account the msx site has the direct link and some background.