New
#11
You would go here:
Official Windows 7 SP1 ISO from Digital River « My Digital Life
and download the ISO that matches the version your PC shipped with---Home Premium 32-bit, Home Premium 64-bit, or whatever it is.
Burn that ISO to a disk. Install from that disk. Activate it with your Product Key.
There is no risk. It's the one way you can do a clean install at no cost. You should probably go to your PC manufacturer's web site and download the LAN driver (Ethernet driver) so you will be able to re-establish an Internet connection following the clean install. The other necessary drivers should be included within the downloaded ISO.
Then go to Windows update and let Windows update itself.
You would have to back up all of your personal data beforehand because it would be deleted during the clean install. The clean install will delete all partitions you now have and create new partitions as needed.
You will have to reinstall all programs. You will lose any programs your PC manufacturer may have included in addition to Windows. You will end up with a legal and activated Windows installation. No more and no less.
When you buy Windows, what you are paying for is that Product Key. Safeguard it.