Had same issue. Was able to do suggestion on another post. My purchased ringtone gone from my iPhone 4S, but it was still in my "Tones" in my iTunes library. I went to the tone in my iTunes "Tones", right-clicked, did "Get Info". Then added a word on to the end of the artist's name. Saved it. Then clicked on my iPhone in iTunes (it was hooked up to iTunes/my computer). Selected "Tones" at the top (this is the Tones on my iPhone) and did a sync of all tones. It worked!