How to be able to get my structure back inside Minecraft's game and mod after changing computer

Hello,

II've made a mod a while ago and I've changed of computer since. I've been able to have my mod back by loading it with a USB key where I had saved it and reinstall the mod by importing the file into the workspace. This mod has structures, and when I'm testing this very same mod by playing into the launcher, I obviously lost all my worlds since I've changed computer, and when I'm trying to load a structure (e.g.: baobab_tree) via a structure block, it says it can't find the structure. I'd like to make the structure appear again so I can look back at it again or even modify it.

Any help?