Why wont my phone let me in by fingerprint?

When I put my phone on my fingerprint scanner it sais that my fingerprint is not recognized this just started happening a day ago and I have previously been able to get in with my fingerprint. Why is this and how can It be fixed?

from Android Forums at AndroidCentral.com - Ask a Question http://forums.androidcentral.com/ask-question/693350-why-wont-my-phone-let-me-fingerprint-new-post.html
via IFTTT