Managing personal Outlook.com account settings, security, and privacy
Hi,
I understand that your step mother lost a gift card in your Microsoft account. Don't worry. I am here to help.
Upon checking, an email will be sent to you once receive a gift card. It includes the code for your gift cards. I would suggest looking for that email to be able to recover your gift card. Another option for you, is to contact the Microsoft support team to help you recover your gift card because they can pull-up your account and look at your account activity.
Let us know if you have other concerns.
Bob