I need some help with my Sansa Sandisk mp3 player. When I first put music on it, it was all very self-explanitory and easy but now that I would like to replace some of the songs on it, I absolutely cannot figure out how. The owners' manual is no help at all. I try deleting songs off it and they show up again. I would just like to erase everything off the device and start from scratch. Any assistance is greatly appreciated.