On title screen press B Rt Lt all at same time
you start another one. I did that by accident once,so then I had to start over
The only way to get the three starter Pokemon on the same save file is to transfer the starter from one file to another game. Then start another file choosing another starter and transfer it over. Then start the third file (after deleting the other ones) and choose the starter you hadn't got yet then transfer the other starters that you had on whichever game.
Start a new game
press up,b,and select or start.
I don't know or care.
To delete your file press B, Up, Select at the title screen. Starting a new game will not work as it will not let you save over your previous file.
I say... don't start over. It's not worth it. But... if you want to spend $40 bucks or something on another Diamond game, then that can be another option, if you want to start over and have come a long way. If you don't like something about in your file that you did, then you can start over. But you have to do Select+Up+B or something like that on the title screen and it'll give you a message about deleting your save file. The choice is really yours. If you like your Pokemon, but want to start over then buying a new game or even a used one from someone else to start over, then that's the only other option I can give you. Sorry if this wasn't much help, but it did give you options and what to decide, at least~
If a file is corrupted there is nothing you can do..you just delete your game and start over sorry.
You must trade it over from another game.
press new game button on starting menuu
An event Pokémon will disappear if you start the game over and delete the save file.
File for bankruptcy and then try and start over. Your credit will be messed up though.