My phone has not been worked on, so how could it have non-Apple parts?

Then you do need to visit your local Apple Store or Apple Authorized Service Provider to have them take a look and provide you with your options. Alternately, as MrHoffman has already suggested, you can use the "Get Support" link.

Contact Apple Support, and discuss your issues and (if needed) repair options.

Whether this is a software problem or a hardware problem will probably require a look.

Use the Get Support link in the upper right of this webpage.

Are you getting a message that there is a "non-genuine" camera? That can happen sometimes. If the part hasn't been replaced or it was done through Apple's official repair ecosystem, that can be reset. It could be a matter of a malefaction including an actual part failure.

zilpha176 wrote:

If I shut down my phone and turn it back on, it will work for a while and then go black again.

Some hardware faults are intermittent. Overall, they don't get better without some sort of repair or replacement.

How are the title and body of your post related? Was your phone repaired by Apple?

If it was repaired by Apple and you see that message then reach out to Apple.