I was wandering how do I make a fresh install of the files.

Do I have to have MW2 downloaded?

What version, can I download it from torrent of anything like that, what else do I need?

Just download torrent with most seeders.

Download a torrent and download the IW4M client from this topic. When both are downloaded, put the files you downloaded from the topic I posted into your game folder and run the "LaunchIW4M"