How do I clean my computer completely and reinstall windows?

I don't want to reformat. I would like to make the computer just the way it was when I bought it. I reformatted my computer, but there was still junk everywhere. I would like to start from scratch.

Thanks,
Ernie

Then Puchase a New Hard Drive or a SSD and start over but there are ways to wipe your old drive but it is time consuming and a SSD would be faster. Also STOP using XP.