Changing username in netplwiz broke my password

I just used netplwiz to change my username. After doing so, I log out and went back to see if the change was visible. At that point, I see on the lock screen that it still displays the old username. Strange. I type my password to log in and keep going, and ... "the password is incorrect"..!

At this point, I am totally helpless since

• I cannot login on to my computer

• I have no other account to log in to, this was my only account on the computer

• I am using the same password since years and I haven't changed it so I know the problem doesn't come from there

EDIT: just to clarify things concerning the accounts on this computer:

• the only account on this computer has always had "Name Surname" as a username
• I used netplwiz to change the name to "Name" only
• On the lockscreen now only one account is available, and the name is "Name Surname", as it always was. Clearly the change of name wasn't taken into account properly.

I suggest:

• Enable the Built-in Administrator in Command Prompt at Boot, which requires a Windows 10 installation USB or recovery drive
• Boot as the Administrator
• Fix your password using Computer Management > Local Users and Groups
• Disable the Built-in Administrator.

Sounds like netplwiz doesn't update the registry correctly and does not alter the username in the registry as last logged on user.

Can you press other account and type in your new username and password? Just because it says the password is incorrect, doesn't mean that's actually true.

Its the combination username+password that is incorrect, but in this case its more likely that its the username that is no longer correct.