Windows 7: I need to reinstall but I lost my discs

I'm not sure if this is the right area to post this in, if its not hopefully someone can point me in the right direction
My laptop is running Windows 7, I'm not entirely sure which version but I've printed off my recovery discs before and reinstalled in the past, my girlfriend and I moved a few months ago and I'm guessing one of us forgot to pack away and bring with us the discs
I did a recovery with the options I had but I can tell it wasn't a clean installation and it still remembers a lot of old memory from my previous installation
How do I fix this, I can't read the serial key as its rubbed off after having the laptop on my lap/bed
Could I buy a new Windows and install that and have a clean install that way?
Thank you

Hello Thequietone, and welcome to Seven Forums.

Yes, you sure could buy a new Windows 7 to do a clean install with if you wanted to.

Before you do, be sure to have all of your laptop's drivers downloaded and saved somewhere (ex: USB flash drive) to have ready to install when you are finished installing Windows 7. You should be able to get them at the laptop manufacturer's driver download page for your specific laptop model.

Have you tried running Factory Recovery from its partition using the key given on first boot screen or in your Manual on the Support Downloads webpage for your model PC? You might even be able to make new Recovery disks. If we knew the PC brand we could have already provided you with the information.

If not then the Product Key on COA sticker was your ticket to reinstalling the OS for as long as the PC lasts, but if it's gone then your only sure option besides buying a new copy is to order the Recovery Disks from the manufacturer.

We have multiple reports that some users with a partially readable Product Key who did a Clean Reinstall - Factory OEM Windows 7 and then used Activate Windows 7 by Phone Step-by-Step Guide were able to get activated with other information provided to the agent. But I would not count on this and only try it once I'd saved a Windows 7 backup image or created a new partition for a test install.

Backup Complete Computer - Create an Image Backup
Partition or Volume - Shrink
Partition or Volume - Create New