Unable to install iTunes updates.

Have been unable to install iTunes updates for several years now. Running Windows 7 on HP G71 laptop. Always get this message: The path...cannot be found. Verify that you have access to this location and try again, or try to find the installation package "iTunes6464.msi" in a folder from which you can install the product iTunes.

When I searched the computer, it found no match for iTunes6464.msi.

Thanks for any advice you may have.