Samsung ML1660 printer stopped working with Big Sur

I recently switch to a new desktop running Big Sur. I followed advice I found in a previous discussion (download driver for ML-2020) which has been working for 2 months, but today the printer suddenly disappeared from my printer list, and when I try to add it back in it is again asking for a driver, and ML2020 no longer appears on the list. I tried re-downloading the driver, but this doesn't seem to have made any difference. Any suggestions? Or do I need to buy a new printer?