Which nVidia product? They made several different ones.
If you're unable to determine which nVidia product you have, open Device Manager, find and double-click the video device (it may be listed under "unknown devices"
if no driver has been installed), click the Details tab, select "hardware id" and give me the hardware id string that begins with "PCI\VEN", (1st./top line of text only).
Another way to get a driver is to tell us what computer brand and model this is for and mention if it's a desktop or laptop computer.