have you tried to select more music to play in the Now playing view, select Options > Go to Music menu.
The music menu shows the music available in the phone and compatible memory card (if inserted).
To refresh the library after you have updated or moved files in the song selection, select Options > Refresh library.
After moving files, if a song has "!" in front of the title, use the refresh option to update the music player.
hope this answers your question...