I have a Dell Inspiron 15 3521. My HD died, and was unable to recovery any files from it. And I don't have any recovery media. And because the Windows sticker on the bottom on the laptop doesn't show a product. I dunno how to get Windows 8 back on it without having to buy a new retail version of it. I tried to do some research, as I know a little bit about computers, I have downloaded and installed windows 7 on my old laptop before and used the product key there for that and it worked. But in laptop i read that the key is built into the bios or something, and there are tools that can get it. And i need a Dell OEM windows 8 dvd. Which is where i started looking, but couldn't find. Can someone help me?