The large majority of neck pain is what clinicians call non-specific neck pain. That is not a way of saying nobody knows what is wrong. It means the pain is coming from the neck's muscles, joints and connective tissue as a system, and no single damaged structure can be reliably identified as the culprit — nor does it usually need to be, because the treatment does not change.
This is the part patients find hardest to accept, and it is worth being direct about: a precise anatomical label is not required for a good outcome, and chasing one often makes things worse rather than better.