I was using it then it suddenly died. I've had it since Nov. 2010 so it's not that old yet. Plugged it into different computers but doesn't work in any of them. It doesn't even show up in device manager. Is there anything I can do short of requesting an RMA?
I am not sure there is not enough information to know what is going on, but you can request and RMA by using the Link on the left.
However I would try format the drive with the Format utility from the SD-CARD Organization. first.