Hi David.
When you move to a new computer, you have to move your rekordbox database to the new machine. To not be caught by an unexpected death of your computer it is key to have a backup of your database and your music files.
A backup in rekordbox can either be made including the music files or without them. It may depend how large your library is. I am preferring to backup without the music files and have the music copied either to another computer or external drive keeping the same folder structure as on the main rekordbox DB.
When I have to restore on a new machine, I am copying back the music files onto the new computer and restore the rekordbox backup to get my database, cues, playlists etc. back. Afterwards I am running the 'missing files' agent to see if all is ok. If not I might need to relocate the database entries with the mass relocation tool.
If you got an exported USB drive only, you may run into trouble as the music file structure on the exported USB might be completely different as that what you got on the old machine.
Can you let us know what type of backup strategy you were having prior you lst you old laptop? Do you have backups from you rekordbox DB and you music files?

