Hey guys, it's been a while. Just about 20 minutes ago I was locked out of my local account in Windows 10 Pro.
In the case that this happens to anyone else, I am going to document how it happened to me and how I fixed it.
What I did:
open current user's "Properties"
I changed my full name from "Felix Wright" to my name. I was told to relog and when I did, two things happened:
1) I as a user didn't exist, although my files and folders still did.
2) I was still able to sign in, but had absolute-zero rights. When UAC opened, the only option I had was to select "No."
After spending about an hour internally screaming, I managed to get home and get cracking down on how to fix this. The reason WHY this happened was that evidently changing your full name removes all user assignments from your user as well as makes your files read-only.
Run Windows in Safe Mode. You can do this by clicking the power button and holding shift until recovery options come up. Select "Advanced" options, and then "Change startup options." You will reboot.
Press 4 to run in safe mode. You will be logged in as administrator.
net user administrator /active:yes
reboot the computer.
Sign into Administrator.
Go to C:\Users.
Right Click your dead user's filename and enter properties.
Remove the highlight from the Read-Only box and Apply this setting to all folders, subfolders and files. Some will deny access to becoming read-only, which is fine. Ignore them.
So, now your files should be editable. Now, to get your account working again.
Right-click your dead account and select "Properties"
Select the "Member of" tab.
Type Administrators and click OK.
Type Users and click OK.
Type HomeUsers and click OK.
Apply settings and sign out. You should be able to access your account oncemore, as well as do administrator-things. Hope this helps on other operating systems, too!