Welcome to Justanswer.com, my name is ***** ***** I will do my best to assist you.
When you start windows 10, is it showing an email address on the sign in page? Or does it only show a username and not an email?
Lets forget the flash stick for now. Remove it.
Then restart the computer, and then on the login screen hit enter so it shows the password ***** with your username above it.
Does it show an email address on that page? ( please doublecheck)
Im here.. apologies for the delay.
May I ask if you are using a wireless keyboard? Also.. when you were using windows 8.1 , did you have it attached to a microsoft account?
Hotmail outlook, msn, etc ?
If you try your gmail password.. It wont accept it?
It may be that you need to clean install windows 10.. Which will wipe out your data and programs, but will get rid of the password ***** get the computer working again.
If you would like to continue this conversation another time, later this week. Youre welcome to do so.
Other then that I hope you enjoy the rest of your Sunday.