Somewhat after the fact, but hard fall on the back of the head caused Loss of Smell. Still can’t smell, although an occasional whiff is detected of cooking smells. Can anyone elaborate on what was damaged, do smell nerves regenerate?

Its called Anosmia the sense of smell originates from the olfactory nerves which sit at the base of the brain’s Frontal Lobes, right behind the eyes and above the nose.

Anosmia by injury to the olfactory nerve. This nerve sits between the frontal lobe and bony protrusions from the skull and is vulnerable to trauma. Damage to the area may occur through shearing and/or stretching of the olfactory nerves and brain contusion or hemorrhage within the olfactory-related brain regions , A blow to the head can also cause anosmia by damage to smell processing cells in the anterior Temporal Lobes or by mechanical damage to nasal structures.
And the sense of smell does come back sometimes