My computer is starting to slow down dramatically, and I want to reformat it.

I purchased a copy of Windows 8 online almost a year ago, and I used a friends hard copy to install it, so I don't have a copy myself.  How do I go about obtaining a bootable version of Windows 8 without repurchasing?

You can use Remove everything and reinstall Windows or Refresh your PC feature.

Thankyou for that. I will give it a try tomorrow once I purchase a bigger hard drive to back some things up!