How to disappear unknown part message

If you have not had the display replaced and the display is original with the phone, make an appointment at the Apple Store or take the phone to an authorized Apple Service shop to get them run some diagnostics on the phone.

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Iobey wrote:

I want to solve or make disappear unknown part message in my phone

About genuine iPhone displays - Apple Support

If you had the display replaced by an unauthorized service provider, the only way to get rid of that message is to buy a new phone.