Which folder does 'iTunes Media folder' refer to? I changed the setting of my iTunes Media folder, temporarily, and now wish to switch it back again. I have many, many music files stored in the following location:

/Volumes/SAMSUNG/iTunes/iTunes Media/Music/{band-name}/{album}/{song-title}.m4a


When setting the preference "iTunes Media folder location", what value should I choose? Is it "/Volumes/SAMSUNG/iTunes" or "/Volumes/SAMSUNG/iTunes/iTunes Media"?

Additionally, when I set this, what else do I need to do to ensure iTunes recognises it - i.e. all my music appears. Choosing either location appears to do nothing, which is partly why this is so confusing - there's no indication if I've chosen the 'correct' folder or not.
You would have to set it too

/Volumes/SAMSUNG/iTunes/iTunes Media


And iTunes will follow through all the Albums and artist. 

Sorry my mistake, thought you could still see your library. That setting only tells iTunes what folder to use to store/organize your files and it would rediscover them if they still were shown in the library.

Because of the change, iTunes has likely lost track of where your files are. The best way to re-add them is to simply drag and drop all the files into iTunes. 

Do you have it set so iTunes organizes your music? If you do only then will this setting really matter for music. Otherwise it just uses the location it was imported from.

If you want to check if it works, try playing a song and see it if can find it.

Or right click on a song and select 'Open Folder Location' (Something along those lines, it is 'Open in Finder' on Mac). This should take you to the location of the song, if it doesn't then it hasn't been set properly.

While not necessary, close and open iTunes to ensure it is updates the library.