Sarma,
You wrote:So the work-energy theorem is dW = -dK is invalid!
Is there not a reaction of the wall on the person?
Yes, of course there is a force exerted by the wall on the person.
THIS FORCE DOES NO WORK ON THE PERSON!
The force is exerted on the person's hand. It exists as long as there
is contact between the hands and the wall.The hands do not move during
the time the force exists. There is no displacement There is no work
done by the normal force from the wall.
the centre of mass of the person does experience a displacement but
the force is not applied at the centre of mass. It is applied at the
hands. the person is not a particle. Thje person is an articulated
body. no work is done on it.
Both Arons and Knight have treated this problem well inrecent years,
(Arons: Teaching Introductory Physics, John Wiley - if you don't have
a copy, buy, borrow or steal one but don't keep teaching physics
without teading it; and Knight: Physiocs, A Contemporary Perspective,
Addison Wesley)