Can't login after changing Microsoft Account E-Mail.

So what you did was change the sign in e-mail, not the login e-mail. The log in e-mail still uses the old address. You can change his Microsoft Account using the steps here:

support.xbox.com/.../switch-gamertag-to-different-microsoft-account

However to do that you will need to use a different e-mail as you can't have 2 gamertags on the same e-mail.

Hello,

Each Xbox LIVE account only has 1 e-mail associated with it. If you're logging into Xbox.com with this gamertag then it means that you're using the incorrect e-mail to logn, or you've misspelled the e-mail on your other gamertag.

There's no way to terminate a gamertag, you can simply change the e-mail address of it if you wish to do so, but you can't delete it forever. If you wish to change the account you're logged into on a Windows Phone you will need to reset your phone. That is
the only one and only way to login to another Microsoft Account on a Windows Phone.

Assuming you have access to your gamertag on your Xbox 360 console, please do the following to find out what e-mail you should be using to login to Xbox.com and to login on your Windows Phone. From your Xbox 360 Dashboard > Settings > Account > Account Information
(3rd Tab) > Account Security > Look to the right, that's the e-mail you should be using to login to your account on Xbox.com/Windows Phone.

Instructions on how you can change the Microsoft account you're logged into on your Windows Phone can be found
here.

You changed the CONTACT e-mail, not the login e-mail. The LOGIN e-mail can only be changed on the console. That being said it sounds like something broke on your account so you'll need to contact support. Most likely you won't get the account back for
a while, so be prepared for bad news.

Ok. Let's say I have 4 E-Mail adresses. 1, 2, 3, and 4. The Mojang account was created with E-Mail 1 and the Microsoft account also with E-Mail 1. But I had also a different Microsoft account with E-Mail 2. Once I changed the Microsoft account with E-Mail 1 to E-Mail 3. And then the Microsoft account with E-Mail 2 to E-Mail 1. After that I realised that Minecraft does't work with E-Mail 1. Then I remembered that I had a Mojang account with E-Mail 1 so I migrated this Mojang account to an another Microsoft account with E-Mail 4. I originally owned Minecraft with the Microsoft account with E-Mail 2(Now 1) and with the Mojang account with E-Mail 1(Now 4)

I'm sorry that it's really complicated.

Even if the e-mail no longer exists it should still log you in as your WLID. You should then be able to change it to your cueernt e-mail, provided you have not associated that e-mail with a Microsoft account. If you have, it's still possible just more complicated.
Let us know if you can login or if you need help updating your e-mail.