Why won't WMP recognize my mp3 player?

Ok i have a sandisk sansa mp3 player that holds about 200 songs and a micro chip thingy inside it that i bought that holds about 100 songs. I got a new computer a few months ago and when i plug in my mp3 player it doesn't charge all the way so i formatted my mp3 player to see if that'll help any. Now when i plug it into my computer windows media player won't recognize my mp3 player and when i go to start>computer and click portable devices it only show the micro chip internal memory and not the mp3 player itself. The same with windows media player it'll only recognize that micro chip and not the mp3 player itself. Now i could only get like 190 songs on there when before i had a little over 300 songs. Does anyone get what i mean? Does anyone know how to fix this problem. Thanks