@germainmukalay there are two possibilities for this. Commonly when your fingerprint scanner fails due to some hardware damage, the option for it will no longer show up in settings. Replacing the scanner will fix that. the other possibility is that this is a software error caused by a recent update. I assume you have not done any, otherwise you would have mentioned this. I'd start by replacing the scanner. Use something like this guide for the repair.

While you work on your fingerprint scanner, take lots of pictures. Once you are done with it, take those pictures and create a guide for iFixit. That will help the next person that has the same problem as you do. It's easy and fun to create these guides. https://ifixit.com/Guide/new The iFixit community will appreciate this.

Repair is War on Entropy!