I'm sorry, I'm a bit confused.
If you mean the crystal, then it's in the inventory after the opening cutscene. Click on it twice, and you should be able to travel forward or backwards in time. I don't know why it has to happen twice, I'm guessing it's a quirk of the game.
If you mean the plant, then go outside, then go to the past, and there should be a prompt of where to plant the seed. Then look in the present and future to see what happened to the seed.
Sorry that you weren't able to experience the game fully! I hope you enjoyed what you were able to experience, though.