iPhone 15 Plus camera button not working

Do you mean the camera icon on the screen does not load the camera, or the software button on the screen does not respond to take a photo?

If the camera loads, can you take a photo with either Volume button?

"iphone 15 plus camera button not working tried doing restart as well not result problem also while using third party app"

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iPhone Camera Button Note Working:

A. Perform a Restart:

Go here: Force Restart iPhone - Apple Support

B. If you are Referring to the Control Center:

1. Go Here: Use and customize Control Center on iPhone - Apple Support
2. Scroll to: To open Control Center, do one of the following:
3. Proceed from there as necessary

Screenshot: