The short answer is that you can't. If you don't have system recovery or restoral disks that don't require the product code to reload your system to factory specifications, and you are now needing to reload your system - it's too late. If your sticker on your laptop, netbook, or desktop looks like this picture you are out of luck and will need to purchase windows again, or use a free operating system like Linux (Ubuntu Preferred). Our recommendation is that when you buy any computer, take a picture like the one below with your readable product key clearly visible and save it ...preferably not on the computer. If your hard drive dies or is wiped, you won't have the picture. Consider printing it out and keeping it in a safe dry place.