login security

My daughter is having a problem login in on her computer. When her computer starts, she is been asked to enter user name(administrator) and password. The password was stored from installation and I have no clue what is going on with computer because I am not there to see it. I need help. I told her to replace the administrator with her name and enter the password she used before, but it does not work.
I need your help
Thnaks