How to Recover a Deleted Minecraft World from Your Recycle Bin
Find the world in your system trash
When you delete a world with this mod installed, the world folder is moved to your operating system's trash rather than being erased. Open your system trash/recycle bin the same way you would for any other deleted file. On Windows, that's the Recycle Bin on your desktop or in File Explorer. On macOS, it's the Trash icon in the Dock. On Linux, it depends on your desktop environment, but it's usually a Trash entry in your file manager.
Inside the trash, look for a folder matching the name of the world you deleted. Minecraft world folders are named after the world, so it should be recognizable.
Restore it back into your saves folder
1. Restore the folder from the trash (use the Restore option if your system offers one, otherwise drag it out).
2. Move the restored world folder into your Minecraft saves directory. You can reach it from the Minecraft launcher, or by navigating to your .minecraft folder and opening saves.
3. Launch Minecraft and open Singleplayer. The world should appear in your world list again.
If the world does not show up, confirm the folder you restored actually contains the world's level.dat file at its top level. If the folder is nested inside another folder, move the inner folder up so level.dat sits directly inside it.