Fable 3 co-op glitch

I used to play Fable 3 a bit on my xbox 360, and then i forgot about it for years and came back a few days ago and logged back onto the account on my series-x.

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I had no problems but i was basically done with the game just needed to do the final bossfight and i had a friend over and i used a different account to make a new game and joined on my account. I then proceeded to quit the game after we played, and the next day, my save was gone and replaced with some other save.

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I have tried most things on youtube and google that i found, and none worked. i just want to know if anyone knows another method since i had every upgrade for my weapons and over 20 million gold that i had accumulated for maxing out houses in the future and other stuff.

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