on interface of ubuntu login [closed]

You seem to be confused by two things.

1. Pressing CTRL+ALT+F2 will indeed sweep you away from your graphical desktop environment to a different input console (TTY).

   Simply press CTRL+ALT+F1 to return to the graphical desktop environment. Be patient. It might take a minute to re-load. Let it.

2. On the F2 TTY, your password is ignored when you try to type it.

   In fact, the password IS detected by the system. The lack of any echo or feedback on the screen is a decades-old security technique.

   Use exactly the same login name and password that you use on the graphical desktop. There is no "admin" account or special password. YOUR account is the admin account; that's why you have sudo.

   If you simply enter the correct password blindly, and press Enter, the system will indeed let you in. However, it will let you in to a shell prompt, not the graphical environment.