Use a bootdisk, such as a linux distro. I suggest Ubuntu... Just burn the .ISO onto a CD/R and boot it up. It should automatically mount your windows partition. There, you can access your files without a password... And you can back it up using an external HD or Flashdrive.
ubuntu download
Download Ubuntu | Ubuntu
Ubuntu documentation
https://help.ubuntu.com/
Also, ubuntu has a great forum... they usually answer any questions in a jiffey..
PM me if you need help..
- Snow Patroll