i do understand that a old belt will break but what coz both belt to break

Well, can you rotate the camshaft at all in either direction ?? .. I can't see any connection between the concealed camshaft drive belt and the external accessory drive belt breakage what so ever! ... Unless engine was being operated WITHOUT the timing belt covers allowing foreign object interference with both belts at spame time (?) .. It is likely engine is damaged since timing belt broke .. Hands-on inspection by qualified personnel IS required! .. IF anything needs to be done other than belt replacement then vehicle is more than likely beyond reasonable repair.