Help with iTunes installation problem?

I just bought an iPod Touch (8GB) and when i tried to work it with my iTunes it said my iTunes was missing components and to uninstall and reinstall. After i uninstalled it, i downloaded the iTunes setup, and it says iTunes is already installed on my computer even though it isn't… So, i checked in my add or remove programs and its not there…. I tried restarting, disk defragmenting, searching for it, and I even made another account to try on there and it still didn't work. Help please?
Nothing. Theres nothing with apple or itunes on my whole computer, i checked twice with the search app. for the keywords also and nothing popped up. I even tried your uninstallation master thing and its not anywheres to be found.