Windows hasn’t support autoplay since XP SP2, i.e. in a very long time, so that explains that part. As for why Windows can’t see the files on the drives today, do you use the USB port for other devices? Windows is notorious for reassigning the same drive letter to different devices. If you can see the devices in Disk Management try manually assigning a drive letter to them. And I suggest plugging in only one drive at a time.
As @mikkirourke noted XP’s support ends soon, April 8 actually, you should make sure you have all the Windows Updates available for your machine by then. And a good independent AV running after then if not already.
