Mp3 device will not connect to my computer.

OK here it is I've had this Sandisk m250 for almost 2 years now and it has worked fine until a couple of months ago. When ever I go to put new songs on it the folder does not show up. I plug it in to the computer with the USB cord and it turns on but when it saids connecting, it goes straight to the first song. My computer can't find the device and I've tried many times to figure out what is wrong with it but I find nothing. Can some one please help me.