Delete files from music box

I don’t have any playlists just single play audio files. There are references to files that are no longer there just

“Warning: filesize() [function.filesize]: stat failed for /home/content/17/7665617/html/wp-content/uploads/2011/12/Sarabanda.mp3 in /home/content/17/7665617/html/wp-content/plugins/flash-album-gallery/admin/music-box.php on line 456
0 Mb”

How do I remove the reference to that file and how do I delete other files? I need to replace the files in the music box with high quality mp3 files.

Are the files stored outside the uploads directory? Thanks for your help.

https://wordpress.org/plugins/flash-album-gallery/