Best way to download a file like itunes without having a problem is by using download managers. Search for any download manager in google and try downloading itunes again.
We help not because we need to but we help because we want to.........there's a big difference between "need" and "want"
Try downloading the program again and if ever you don't ant to use download managers i suggest you download it using either mozilla firefox web browser or google chrome. IE web browser downloads are usually incomplete and sometimes with errors or even virus on it.
After doing so the advice i told you kindly update this post.
We help not because we need to but we help because we want to.........there's a big difference between "need" and "want"