Why won't my Tokina 100mm f/2.8 Macro autofocus on a Nikon D7500?

Check the simple mechanical and AF settings first. On this Tokina macro lens, autofocus depends on the lens being mounted correctly and the AF controls being engaged. Make sure the lens is fully seated on the mount and rotated into place normally—do not push it inward while mounting, as improper mounting can prevent autofocus coupling from working correctly. Also check that the lens’s AF/MF switch is set to AF, and that the camera body is also set to autofocus. This Tokina version relies on the camera body’s AF drive, so both the lens and camera settings matter. If the lens was mounted incorrectly, removing it and remounting it properly should restore autofocus.