In most cases, you do not need to make a negative to get new prints from scanned black-and-white photos. Since your starting point is already a digital file made from a print, the best quality you can usually get is to print directly from that file through a photo lab or print shop.

Making a new negative from a scan of an old print adds another generation, which usually means more loss of detail and tonal range. A print already contains less information than the original negative, so scanning the print and then converting it back into a negative is generally not the best route for normal reprints.

If your goal is alternative processes such as contact printing, people do make “digital negatives” by inverting the image and printing it onto transparency film. That can work for contact prints, but it typically won’t give the resolution needed for a useful 35mm or 120 film negative.

So the practical advice is: take your digital files to a local print lab and ask for prints directly. Only look into digital negatives if you specifically want to do contact-printing or alternative darkroom processes.