virtualbox.org

After set every settings about virtual disk, i choose my new Windows 7 virtual machine and start it; but it will appear a text message that say "a drive is missing..."
What Can i do?

Driver missing would indicate a corrupt install media. Where did you get it from?

I don't rember the site, i could redownload it, from which site i Can get Windows 7 iso free?

Windows 7 is a licensed product and you can not get it free, unless you want a trial version and you would get that from Microsoft. We don't discuss pirating software.