Android - How do I change incorrect album art on the default Music Player of the Samsung Galaxy S III?

What worked for me, as adx suggested, was to go into the /Android/data/com.android.providers.media/albumthumbs folder on the phone and delete all of the files it contains. They are extension-less files, so it is impossible to tell which one is the offending one, so I just deleted them all. The next time I opened the default Samsung music player, all of the album thumbnail images at first appeared empty, then after two or three seconds, the music player re-generated all of them, and my new album art appeared on the offending album.

(This was after I "showed hidden files and folders" via the control panel in Windows and deleted the AlbumArt.jpg and Folder.jpg files that were there)

Force stop your Music playing app. Connect your device to a PC. Use the search function to search your phone (phone storage or SD card where you store your music) for albumart.jpg. I use Linux so the results appear as icons, in Windows right click - search . You can delete the offending icons, then use whatever app you use to try find new album art. You can be more specific by searching: \albumthumbs , \android\data\com.android.providers.media\albumthumbs and of course each individual album folder.

This is the solution I came up with.

First, it seems that album art is cached, so after deleting the offending album, closing the music player, and restarting the phone, it might still persist. In this case, leave it for a day and try again.

Second, go to Folder Options / View / Advanced Settings / Show hidden files and folders. and uncheck Hide protected operating system files (recommended). Delete Folder.jpg, AlbumArt.jpg, and AlbumArtSmall.jpg in the offending album's folder (and any other jpgs that represent the old album art. Usually they have UUIDs for names).

Third, make sure there is an AlbumArt.jpg representing the correct album art in the album's folder. Ideally, AlbumArt.jpg should be a perfect square.

Fourth, try copying the album's folder back to the phone. If everything in the first step was tried and the album art has not changed, I would suggest changing the album's name. Technically, you're adding a new album at this point, but at least it will have the right album art.