I had Chin liposuction four days ago still numb???

Numbness is expected after liposuction as the passage of the suction cannula underneath the skin interferes with the sensory nerves to the skin.  The nerves heal over time, but it is one of the slowest elements of healing and may take months for the complete return of sensation.  You should consider discussing the matter further with your operative surgeon.  Best of luck with your continued recovery.