Lost Gamertag. Lost purchases as well. I think i factory reset.

Each gamer tag is tied to a unique email address. If you're seeing a different gamer tag then you didn't sign back into your Xbox with the correct/original email address for your account.

To get your stuff back, you need to find that original email address.

You can try these steps here -
https://support.xbox.com/en-US/my-account/microsoft-account/forgot-microsoft-account-solution

You can also try an contact Xbox Support and provide them with your original gamer tag and they can try and help you locate your account.

You can contact Xbox Support here -
https://support.xbox.com/contact-us

If you're in the states you can call them at 800-469-9269

I feel you I lost 700 out of 1000 worlds to a factory reset

A few things you could possibly try.

1. Deleting your profile and reinstalling it to the console, then setting it as your "Home Console."

2. Submitting a support request for the tech team (and hope they don't send you back here) https://support.xbox.com/en-US/contact-us

3. Or as a last ditch effort delete everything off your hard drive (or the game/games effected) and then reinstalling them.

And after verify if you are logged with the corrected account from where you bought the game, if doesnt appear in the Ready To Install bar, try search Grand Theft Auto 5 in the store through the console and see if appears available the install option.

Hi Paul.

Thank you for reaching out to the forum. Sorry to hear that you are having issues with you purchases. You have to reach out to
support.xbox.com to get the issues resolved.