If the railings are just separated at one end but still present, it should just be a case of carefully reglueing them. PVA or superglue. If they are just regular matchstick colour, replacement should be no problem. If the rails are smaller section than matchstick size, thats what sandpaper is for.
For the other parts, if they are still present, refixing should not be a huge problem, apart from figuring out just how they should fix. Missing parts are an entire different story, since from here there is no way of telling if the "other" coloured wood is naturally that colour (redwood matches?) or a stain, and just what wood or stain was used.
For something as good looking as that, it needs doing right.