It sounds like there's some kind of error with your phone. I would advise the following steps:
1) make sure the camera lens is clean
2) do a soft reset by holding volume down button and power together.
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make an account on Windows Central so that you provide more information for us to better help you.
Please share what phone you have, what OS (Windows Phone 8.1 or Windows 10 Mobile) and if step two worked for you.