When you say that iTunes doesn't open, do you mean that when you click or double-click on the iTunes icon nothing happens, or you get an error message?
Try opening iTunes from its install folder e.g. C:\Program Files (x86)\iTunes\iTunes.exe
If it opens correctly then it's a problem with your shortcuts.
If not then I'm not sure what it is. Have you restarted your computer since installing? Sounds silly but sometimes that helps.
I've had issues like this in the past and it turned out that the hard drive was faulty.
If nothing else works try this free software to see if it may be your hard drive:
http://www.softpedia.com/get/System/Hard-Disk-Utils/CheckDisk.shtml