Arrrrg Vista! Damn pass.

I'm freeking out.
My dad's computer now has a password...Which none of us ever set. I don't know why it ever appeared, and we need acces to the account. What can I do?

I tried booting on my Flash drive, but for some reason it won't show up in the BIOS, even though it works fine on an other computer.

VIsta by the way.

Oh yay. Turns out a BSOD reset it to the pass which was on about 2 years ago... FOund it.

I was gonna try out a bootable CD anyway.

Right. Spoke too fast.
Now it won't even boot. Blank screen - but it is on. No BIOS, nothing. No noise, not even when I randomnly type on keys...

What should I do?