Offline NT Password & Registry Editor is a very fast password "recovery" program. I quote recovery because the program doesn't actually recover the password - it deletes it. This is a bit different than other password recovery tools like the very popular Ophcrack.
For a quick overview, see my complete review of Offline NT Password & Registry Editor.
Offline NT Password & Registry Editor is a program that deletes passwords so the first thing you'll need to do is visit the Offline NT Password & Registry Editor website. When the website loads as shown above, scroll down to the Download section and click the link next to Bootable CD image - in the example above, that would be the cd110511.zip file.
Note: Since you obviously can't access your computer right now because you don't know the password, these first three steps will need to be completed on another computer that you have access to. This "other" computer will need to have access to the Internet and the ability to burn a disc.
Another Note: This is a complete tutorial on using Offline NT Password & Registry Editor to remove your Windows password but I'd highly recommend that, before you even get started, you walk through the whole process once just to see how it'll work.
Offline NT Password & Registry Editor is completely text based which can be a little intimidating. However, anyone should be able to complete the password reset process using this tool as long as you can follow along with these instructions.
Note: A program called PC Login Now works in a very similar way to Offline NT Password & Registry Editor and is much easier to use. However, it causes Windows to detect a hard drive problem which doesn't seem to actually exist but is a little concerning nonetheless. I highly recommend that you try Offline NT Password & Registry Editor first even though it is a bit harder to use.