I have a Sansa Fuze. When I open the internal drive, I see music files listed. Some of them do not appear on my player.
What filetype are the “missing” songs? The Fuze supports MP3, WMA, WAV, OGG, FLAC and Audible. Audio files in other formats will be ignored.
If they are any of the suppported file types, then look in Unknown. Unknown means the Sansa has the file but no tag information. The files may not be tagged so the Fuze can read and list them.
Search the forum for “ID3v2.3 ISO-8859-1” and mp3tag to learn about fixing tags.