Windows 7: [Win7 x64] Forgot My Password/Cannot Re-Install Windows

I forgot the password to my account(No password reset and tried using the cmd but it wouldn't work either) a while ago so I'm on my guest account and I was going to just reinstall windows 7(Also tried booting from disk) but when I put the disk in it said I cannot, so can anyone tell me how to do either of the following;

1) Install Windows 7 without administrator rights
2) Recover/remove the password from my other account (I have managed to get an encrypted version of the password)
3) I also would be open to completely wiping my hard drive as well and doing a fresh install of windows as I have a back up on an external HDD.
Either will resolve my issue so whichever option is easier to resolve.



System info
OS: Windows 7 Home Premium x64
(I don't think there's anything else relevant other than OS but if so, ask for it below please)

I appreciate any help I get, thanks

Just one thing that seems kind of fishy to me. How do you forget your password? You use it everyday. How do you forget it?

Please read rule #6.
Windows 7 Forums - Forum Rules

My passwords are made with random.org so like one of my old passwords would have been "3mStafjM7" or something like that and I had just started using a new password and I forgot it one morning, I know about 5 letters but that's it unfortunately

I'm not hacking, this is my own system that I built, I can take a sreen shot and show you that the are only two accounts, "Kristopher" (Myself) and "Guest" although even if I had information on how to completely wipe my hard drive so I could re-install windows would be useful.

For a Clean Reinstall of Windows, follow gregrocker's helpful tutorial.
Clean Reinstall - Factory OEM Windows 7

I tried this but it didn't work unfortunately. It booted frm disk (With my windows 7 install disk in the drive) and it took ages but then it went to the log in screen, I have pictures on my phone. I'm trying to get them up now but I need to install the driver software.

Did you set your BIOS to boot to the CD/DVD Drive? If so, you shouldn't be getting a log in screen.

Yeah I did, I set it to priority and I also tried when it was starting up to boot from CD, I really don't know why it isn't working because it seems to work for everyone else, I must be doing something wrong. Could it be because I built the computer myself or something? Like it doesn't have manufacturer settings etc?

Try reburning a DVD at slowest speed possible using ImgBurn or the Microsoft USB/DVD Download Tool. If the second DVD doesn't work, use a 4GB+ USB Drive. Download link for the Image File is in the tutorial.