Installed Windows 10. Now I cannot open ITunes.

This may be the result of a corrupt preference file causing iTunes to attempt to open the wrong file. Hold down shift as you start iTunes, click choose, and browse to the folder that holds your library, then open the .itl file inside it. If the problem persists see Repair security permissions for iTunes for Windows. (Looking again this may well be needed because of the upgrade.)

See also Empty/corrupt iTunes library after upgrade/crash.

tt2

similar issue - iTunes wouldn't open..at first it was giving me the message "iPhone cannot be synced...", then after reboot, it would open and close immediately. Re-downloaded iTunes and ran "repair" and it fixed my issue....

See also Troubleshooting issues with iTunes for Windows updates.

tt2

What is your Music folder doing inside Program Files (x86)?

Your iTunes library folder should normally be in C:\Users\<User>\Music\iTunes.

tt2