I phone touch button

If you open Settings -> Touch ID & Passcode, is the button for enabling TouchID grey or dimmed out?

If it is not disabled, can you set up new fingerprints?

If the Touch ID button does not recognise your fingerprint at all, try these steps first, before you contact the Apple Support or an Authorised Apple Service provider to get this fixed.

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Follow these steps. Try using Touch ID after each step:

1. Make sure that you have the latest version of iOS or iPadOS.
2. Make sure that your fingers and the Touch ID sensor are clean and dry.* For the Touch ID sensor, use a clean, lint-free cloth to wipe off any dirt or debris.
3. Your finger should cover the Touch ID sensor completely, touching the surrounding metal ring. While Touch ID is scanning, you shouldn't tap too quickly or move your finger around.
4. If you're using a case or screen protector, make sure it doesn't cover the Touch ID sensor or the surrounding ring.
5. Go to Settings and tap Touch ID & Passcode. Then make sure that iPhone Unlock or iTunes & App Store is on, and that you've enrolled one or more fingerprints.
6. Try enrolling a different finger.

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copied from: If Touch ID isn't working on your iPhone or iPad - Apple Support

If still no luck, your iPhone has to be serviced, if you want to use Touch ID. Only Apple or an Authorised Apple Service Provider can pair a new finger sensor to the rest of the hardware of your iPhone.

Apple Support online

You can also contact the official Apple Support directly by giving them a call:

Contact Apple Support - Apple Support