This happened to me recently and the best way i found to fix it is these step
Make sure you havent deleted the folder with your save data first
1. Go in the main folders GrowthRPG Folder
2. Open Save then Go into Saved games
3. Make sure you copy the Save0 File
4. Delete that folder then extract the game again
5. Open the game make a new save on the empty file you'll get when you first start
6. Close the game
7. Copy your Save0 File over the New Save0 File
If you did everything right it should open the game with your save file
Im not sure if this is how everyone transferred saves before but i do know that this primitive thing is caused by something in the settings
I hope this helped