My laptop in example had a keyboard with no number pad. If it is a laptop I've seen a key combination disable it as well if it is inside the actual keyboard and not a separate 10 key. Had to do this on several of our Dell Laptops here (only once each though). Never figured out why it quit working though. That restored the 10 key but I would have to do that every 5-6 months. I ended up removing the keyboards from device manage and letting windows rediscover them. At first I thought it was the 10 key and swapped it out but that didn't fix the issue. I had an issue on one Dell consumer grade laptop with Win7 two years ago where a usb 10 key with a built in usb hub would occasionally quit working.
