Ron, the files can be saved in folders on a USB thumb drive using windows explorer. This will save them alphabetically/numerically.
For midi files, save by song title, or artist - it's that easy. Of course the files have to be appropriately named to do this.
Same is true for style files. You can save these in categories and separate folders, or for third party styles, rename them to an appropriate song title, which is what I did many years ago when I created gig disks. I created the gig disks because I had hundreds of third party style files, many of which were very good, but there was no way to determine which style fit which song the best by simply scanning through the styles. By renaming them with song titles that fit them, it was just a matter of looking for the song, similar to a midi file.
If all of this is stored on a USB drive, be sure to make a backup USB drive - just to be on the safe side. My USB drive stays in the keyboard, and everything can be selected directly from that drive in the blink of an eye.
Good Luck,
Gary