windows 8 media center pack

I paid Microsoft for a media center pack and used it but because my laptop was only loaded with one laugauge software by acer i tried to restore my software and ended up messed up the laptop i took it to it shop and the tech wipe my hard drive clean and loaded windows 7 he said this was the only way then he reloaded it windows 8 pro.
i still have my windows 8 media center pack key how do i get to down load the pack again please help