This guide will let you know how to complete the Lost In The Dark Grove quest in Disney Dreamlight Valley.
First of all, you have to go into the big dark void and save Donald.
When you reach the other side, there will be something on the ground, a feather.
Pick it up and go back to Kristoff through the void. After that go to Merlin and he will want you to get Donald’s feather which you already got then dream shards and a plant from the dark grove and two emeralds. 
So go back to the dark groove through the void and you’ll find a plant on a tree, as shown in the picture. After that, go find the emeralds in a glade of trust and forest of valor and take someone with you who has a mining bonus.
Once you get the emeralds, you need to continue and find Merlin. You just have to use Donaldson’s feather to light the way.
When you find Donald, you’ll get the orb that you need to go ahead and place in the stone near the void.
That’s it, the quest will be completed.
