It's easier to do with a query. Something like

SELECT Left(State.Reg_Code,3) AS Reg_Code ;
  FROM State ;
  WHERE Left(State.Reg_Code,3) NOT IN ( ;
    SELECT ccRegion.Reg_Code FROM ccRegion) ;
  INTO CURSOR crsNewCodes
SELECT ccRegion
APPEND FROM ( DBF("crsNewCodes") )
...

>
>How to use Scan .. endscan to replace in the following codes which are
>worked fine ?
>
>
>

>Select State
>Go Top
>Select ccRegion
>Do While !Eof("State")
>
>	Locate For ccRegion.Reg_Code = State.Reg_Code
>	If !Found()
>		Append Blank
>		Replace ccRegion.Reg_Code With Left(State.Reg_Code,3)
>                =TableUpdate(.T., .T., "ccRegion")
>	EndIf
>	Skip 1 In State
>EndDo
>

>