My computer only opens certain programs. It can open IE, Paint, Explorer, and some others that I need to check. I can't open other programs like Malwarebytes, Chrome, AVG, and others. I get error popups when I open those programs. I also can't uninstall any program. This all happened after I uninstalled iTunes and downloaded (not installed) a new versions of iTunes. Any solutions?
Could try elevated CMD with: sfc /scannow Upgrading to the same install will replace your OS and leave everything as it is apart from drivers
Are you by chance using Windows 7 Starter? Do you possibly have a System Image from a time your computer was functioning properly you could restore? Maybe even a Restore Point you could revert to? If you have the installation media, maybe do a repair install.