It would seem that perhaps a good first step might be to reclaim your Gmail account.
Evidently it is a bit of a pain, but certainly doable with a little time and patience according to this
https://productforums.google.com/forum/#!topic/gmail/lcJQFla9y8E
You might be able to rescue your computer by enabling the normally hidden / disabled Administrator account and use that to possibly fix the password problem on your local user account.
You'll need to boot from the installation media. If you do not have the installation media on hand you can download the ISO from here
https://www.microsoft.com/en-us/software-download/windows10
Once you have the ISO, you can use ImgBurn to burn it to a DVD,
http://imgburn.com/
or Rufus to burn it to a USB ThumbDrive,
http://rufus.akeo.ie/
either of which you can use to boot your computer.
THEN...
Follow the steps outlined here
http://pureinfotech.com/2015/11/20/how-reset-windows-10-forgotten-password-regain-access-computer/
Personally I wouldn't have chosen to link my Gmail account to my primary login to my Windows 10 machine.
I know a lot of people seem to do that but I don't think that generally it's a good idea. I think using a local account initially is a better idea and at a later point if you find that you need a more robust user to take advantage of some of the other features and functions of Windows 10, creating an actual Microsoft Account (
[email protected]) and then using that by simply choosing to login with a Microsoft account instead by going to Settings -> Accounts -> And choosing the link under the local account to perform that task.