How to go from scene to another than back to the first scene right where you was

Godot Version

Godot 3.2.3 (or any Godot 3.[not Godot 4]

Question

you walk up to NPC. He(or she) ask you do you want to go on an text adventure with him(or her)

you go on the the adventure then return back to where the NPC was..

You would have to store this previous destination in some semi-permanent data like a variable in an Autoload/Global script

If you’re just going to change the player’s position, then you can store the player’s global_position in a Singleton and when the text adventure ends and you load back the original scene, move the player to where they were by using the global_position variable you stored.

Also a very easy solution for you. The text adventure is probably very light, you can just add it to the main scene and hide it. And when the text adventure starts, just show it and pause the rest of the game. This way, you don’t have to change scenes. When the adventure ends, just queue_free() the text adventure.