I have 1 music file that I can drag and drop into the music folder, then disconnect the Fuze+ from the USB port, let it load, etc. and the file is not there.  It’s the only one that this has happened with and I’ve been put lots of files into the player in the last few days.  I’ve checked everything on the file (titles, track numbers, etc.) and it looks fine.  I have another file by the same artist and when I selected his name I expected to see both files, but alas, not there. Any ideas?

Check the ID3 tag. The player sorts by these tags, NOT by the file names. Look to see if you have an UNKNOWN folder, and if so it’s likely this file will be in therre. The player puts files under this categaroy if for some reason it cannot read the tags.

It might be the wrong format, or have strange or foreign characters in it, too much data in the Comments field or embedded album art that is too large. Anhy number of things can cause the player not to be able to read the ID3 tag.

MP3Tag is excellent, free tag-editing software.

Don’t know what ID3 tags are.  Can you explain?