Original post by: Minho ,
When you boot the device, does it give you an error message saying that there is no TouchID? If it does, then the TouchID sensor in the home button is damaged. If it doesn't, then the problem may be software related. I would try a hard reset (Lock/DownVol buttons for ~10 secs). If that doesn't work, do an iOs update if available and eventually, try a full backup/DFU restore to see if that helps. If none of that works or you get an error message, then you will need to take your phone to an Apple Store for a new TouchID sensor. Only they can program a new button.