I never needed a userid or password to reinstall Windows from the installation CD or recovery media.
This story, by the way, shows how useful it is to have 2 user accounts with administrative capabilities. When your regular one doesn't work anymore, you just use the spare one. An idea to keep in mind when you're up and running again.
Kees
I am no longer the admin of my own computer and whenever I want to connect to a wifi network, I can't see any other wifi from my laptop but I can see it from my phone and other devices. It just doesn't appear at all so I got no network to connect to. So I tried to reset my laptop since I already backed up everything and I am not an admin anymore?? I can't install anything without permission, even when I want to click on "open system restore" I need permission. A box will appear and I have to type in a username and password which Idk and don't have. Then at the bottom of the box, it says "Domain:RP". HELP I'm freaking out

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic