All you'll need is a drive that can burn CD's (most computers made past 2000 would have one) and a blank CD. You'll also need the internet and enough download allocation to download 450 MB.
Kudos to T. Fairbank, who introduced me to the idea.
Disclaimer: Do NOT do this on a computer that is not your own. That would be bad. Also, please do not sell this idea to people, as many people do on the internet. Try to keep this running between people you know who may have this problem.
If you need any help or have any criticisms, especially on grammar and punctuation, they are much appreciated.
P.S. Please refer to my other instructable if you are looking for a quick solution for XP only.
Step 1: Download the Image.
Step 2: Burning the Image to a CD
Go to the ImgBurn Website and click on the download tab on the top of the page. Then, choose any mirror from the list and download the program. It is approximately 2 MB, so shouldn't take long. After that, run the installer.
When you've installed the program, run it and choose the option on the top left, which is Write Image file to disc. This is shown in the second picture. After this, under the source heading shown in the third picture, press the browse icon and browse in the download directory for the file. Then just make sure the destination drive is the correct CD drive, insert a blank CD and make sure verify is ticked, then press the image which is underneath with a CD on a page, a right arrow and a CD. It should start to burn.
Step 3: Allowing the Computer to Boot From a CD
(A quick note: Some computers have a button listed that boots from CD, like some lenovo's, which ask you to choose a temporary boot device with the enter key)
To start with, when your computer turns on it should ask you to press a key or a number of keys to "enter setup" or "enter BIOS" or something along those lines. You need to press these. Some common ones are Delete, F1, F2, F10, Ctrl+alt+Enter or Ctrl+alt+Esc.
When you press them, it should now show a screen like one of the pictures below. It will either be in a tab like in the last image, or in Advanced features or Bios features. Follow your Bios instructions on how to rearrange the items. It normally uses + and - which move the item up and down the list. Move the CD Drive to the top of the list, followed by the Hard drive. Take note of the original order, and if the computer doesn't boot afterward, just arrange them in the original fashion.
1. My keyboard won't work : Try using a PS2 keyboard (the type that isn't USB and has some pins in a circle)
Step 4: Boot the CD
Now comes the easy part. Just sit back and wait for the progress bar to finish at the bottom. Then if you look in the NT Pwd list, your password should be there, in the list with your username.
After you have the password you need, you can simply press on the section like the start menu and select turn off, or something similar and it should shut down the computer. Then just switch back the priorities if you'd like and then You're Done!
Step 5: Enjoy!
Thanks to T. Fairbank again, for the help in finding an easy to use live CD.