TYE WAY TO allow you to use mp3 files in the memory card

sprint does not allow you to use mp3 files in the memory card as ringtones. they block that in order to make more money.Since your phone used to be sprint, that is why it will not workthe only way is to follow the above tutorial fromventones and convert the mp3 files to a video file. then transfer that to your memory card. ventones is the only free ringtone site that allows you to do that. its awesome!