Not missing, just doesn't want to be found...classic addict behavior. Unwilling to live and too afraid to die. Just making it all a blur of semi-conscious passing moments of minimal feeling of pleasure just to avoid real feelings of anything. There is no help for them that can be given until they are ready to receive it.
Like a drowning person, you can't save them until they extend their hand asking to be saved. Otherwise all they will do is wear you out and drag you under with them.