I download the service pack 3, i start the computer, it show i have to sign in with password,but i never have any password before,how do i can get it??2 people need an answerI do too

I download the service pack 3, i start the computer, it show i have to sign in with password,but i never have any password before,how do i can get it??I am having the same problem..My boss is away and I cant get on my computer so I can do my work UGH!!!!!