how can i get my gamertag back?

Hi,

You need to pay for a new gamertag you can't change your gamertag for free or you can contact support on this issue

I'm not sure you'll be able to, but you can try to contact support
support.xbox.com

Also keep in mind even if you can change the tag you might not get the tag back. If your friend changed your tag I would recommend to not game share.

Hi nickstanton2,

Thanks for reaching out to us in the forums with this issue. In relation to any changes made to a Gamertag, if you've already used your initial complimentary change, then any further changes made would need to purchased. This means that even if you were
game sharing with someone and they made the change, in order to change the Gamertag to something different you would need to pay the fee (which varies by region). Please also bear in mind that when game sharing, your profile need not be logged in and that
you should never share your password with anyone in order to keep your account safe.

How to change your Xbox gamertag

Gamertag update FAQ

To prevent occurrences like this in future, I recommend that you create a passkey on your accountso that any further changes to your account cannot be made. Here are a couple of support articles that you may find useful for keeping your account safe when
game sharing:

Require a passkey for purchases on your Xbox One console

Create an Xbox One passkey

I hope that this information helps you out. Let us know if you have any further questions.

Hello Jessica,

Thanks for coming to the Xbox Forums. As of the
new update, you will not be able to change a gamer tag back to over 12 characters long. There would be no way of getting the old one back. Even support are unable to change a gamer tag. We are truly sorry for the inconvenience.

As there is nothing we can do here on the forums. I will be locking this thread.

Thanks,

Brad