I recently changed the name of the administrator and turned off passwords then clicked lock.

After some time, I decided to add a password so I clicked on unlock and it's prompting me to enter a password.

I tried typing the old password and it didn't accepted it. I also tried to set password and keys as "set to default" but still nothing happened.

Now I'm stuck and can't get to change the administrator settings. I did my research but nothing seems to work.

Please help.