Hello, thank you for reaching out to Microsoft Q&A.
May I please know whether Microsoft recognizes you as a child account?
And did you recently reinstall the Microsoft Mahjong game from the Microsoft Store?
If you have synced your game data to your Microsoft account, ensure you sign in with the same Microsoft account.
In the top-right corner of the app, select your Xbox gamer tag picture, then select Sign Out.
Then sign in with the same account you used before to play the game.
Let me know if you still need more help.