The ID Touch is part of the home button and unlike the home buttons in the past iPhone models the ID Touch hardware on the home button ribbon part is linked to the A7 microprocessor on each iPhone 5s logic board. So, in other words the ID touch hardware is married to the A7 chip and is unique to each iPhone. This is why you can not change out the home button part to get the ID Touch to work and why after replacing the part a reset loses the feature in Settings altogether. If you have a home button function failure you can change out the part and get that function back, but you will lose your ID Touch function permanently. If you have lost your ID Touch, it is gone, not even Apple can fix that they will give you a new iPhone if it falls under AppleCare. Apple prides itself on security i.e. iCloud and now ID Touch. It is very very secure and like iCloud has it's drawbacks when legit iPhone owners forget there ID and PW, so does the ID Touch have its drawbacks when a malfunction happens. It's simply just the way Apple designed these devices. Thanks - iRepairsIt.com