Camera issues

Change your Photographic Style

• Want to change the Photographic Style that you set? Just open the Camera app, tap the arrow , and tap Photographic Styles . Standard is the default, balanced style that's true to life and can't be customized, but you can swipe left to view other preset styles that are customizable. Tap Customize  to adjust the Tone and Warmth of the style that you've chosen.

Which iPhone model do you have?

Did you already try to force restart your iPhone?

Force restart iPhone - Apple Support

To rule out a software issue, set it back to factory settings, using your computer. After that, set it up manually, without using the latest backup and test the camera.

Restore your iPhone, iPad, or iPod to factory settings - Apple Support

If the zoom function is back, restore from the latest backup and test again.

Incase setting it up as a new device without using the backup does not bring back the 0.5 zoom function of the camera, you should get the phone diagnosed by Apple or an Authorized Apple Service Provider next to your place:

iPhone Repair & Service - Apple Support

Apple - Find Locations