Why is my fingerprint sensor not working and not showing in settings

@sam10272 I'd start by restarting the phone. Next you want to check if your phone's software is outdated. Go to "Settings" > "Software update" and check for any available updates. Then you have to consider that Xiaomi has even turned it off in and update. Xiaomi has a lot of bugs with their fingerprint sensor and software. Of course then there is also the possibility of this being a hardware issue. If your sensor has failed your software can probably not find it.

Since iFixit does not yet have a guide for this, use something like this video to replace it.

While you work on your phone, 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.