Greetings, Kayella
Aditi beta grid profiles, inventory, cash balance, are all fake. That is to say, they have no physical connection to the main grid, are like a shadow, a memory.
If you have truly lost/deleted a folder in your Agni inventory, and have tried everything suggested to retrieve it, including contacting Linden Lab support directly, who advise you that you are out of luck, then I am afraid you are out of luck.