Need help with transferring a lost Microsoft account with my old gamertag.

That is why you need create a new one just to get pass to the form. Then if the info you provide is enough the system will match it to the actual lost account

Hi! I'm Luis, a fellow Xbox Gamer . Thanks for reaching us out here.

Do you remember if you registered either a phone number or alternate email to the account?

If you do then you can use it to get part of the email to help you remember

At the log in page:

Sign in options>Forgot username>Enter alternative email or phone number

If you did not register any alternate email or phone number then you need to go with the account recovery form

https://account.live.com/acsr

Here are the detailed instructions and tips to fill the form

https://support.microsoft.com/en-us/account-bil...

You will need to create a new one just to get pass to the form. Then if the info you provide is enough the system will match it to the actual lost account

I can't remember the email I had associated with the Gamertag so I don't know how I would complete the account recovery form.

Hi DannyTubiolo,

I believe that you can not transfer a gamertag as it is linked to your Microsoft account/email.

You will need to use the Microsoft account recovery form and try to recover the lost account/password.

Which gamertag is linked to your Microsoft account? The new one or the old one? My guess would be that your old account is still linked to your Microsoft account and you are trying to use the new gamertag but the old one is interfering. Check this link out
on transferring gamertags
support.xbox.com/.../switch-gamertag-to-different-microsoft-account. If that isn't the issue come back and let us know if we can help further troubleshooting the issue.