Vista - no textbox for password

I made an administrator account on Windows Vista Home Premium.
Since then I need the administrator password for all kinds of
activities.
I know the password, but regrettably the window that asks for it has
no textbox to enter the password into.
In fact, the only thing that can be done with this window is to close
it and to cancel the operation.
How can this be solved?

Did you try logging on as guest, there must be arrow to change user?

Wait ,, you need to go to user accounts first,,