Windows 7: UAC and administrator password

Windows 7 on aspire one
The administrator account is hidden.


The UAC prompt appears on the darkened Secure Desktop screen. I am asked to type an administrator password and then click Yes.

But there is no password field! There is no username field! There's nowhere for me to type my credentials! I am unable to click "Yes," and my only option is to click "No" to cancel the UAC elevation.

I have tried the suggestions found in the forum already. Something seems to be missing. I have realized that I do not know the username of the administrative account. Only the password. So if I try holding down the shift key while clicking on a program and the option is to switch user, I cannot switch to administrator account. Thinking that I would not be able to anyway because it is hidden and disabled. My brother gave me the computer and just told me the password. He does not seem to know anything else. Cannot use elevated command prompt. Is there another way? Thank you so much!

Control Panel/User Accounts/Manage another account

What do you see there?

Can you open the run box and run control userpasswords2 ? What accounts are displayed?

Thank you for your response. Here's what happens.
1. Control/User Accounts/Manage another account. Answer: Same dialog box appears. "Do you want to allow the following program to make changes to this computer? To continue, type an administrative password and then click yes" The only option highlighted is to click no. There is no place to type in password
2. Control userpasswords2 in run box. Went to command prompt and typed that in. Did not display any information.

You can search Windows 7 Password in google and then you will get lots of results.

If you go to control panel, user accounts, does it say "Administrator" under your account name? It kind of sounds like you are a "Standard User" instead of admin. Just type control userpasswords2 in the run box, not from the command prompt.