Damn... 60 years old... Never owned a computer in his entire life... robocop, this is the very definition of an impossible task!
I'm pretty familiar with Linux, although I've never actually extensively used one of the distros. I use Windows
8, like a weirdo.
I actually use MSYS2 often, which is a minimal POSIX emulation layer that includes many different utilities and programs that are common on POSIX distributions, but run on Windows. Because of that, I'm pretty well versed at writing shell scripts (bash). I also use gcc to compile my programs, and use vim to write the source code.
Now, I'm not sure if I'd ever recommend a novice computer user to use Linux, as there are many aspects of it that require knowledge of how to use the shell / command line. Out of every possible distro,
I'd recommend Mint, because it targets mostly novice users.
A big problem with Linux is it's poor driver and hardware support (because manufacturers neglect Linux, imaginably for nefarious reasons). For instance, sometimes the available Linux drivers for certain WiFi cards are of mediocre quality, and aren't able to take advantage of the card's full power, thus limiting the range of the signal receiver.
Other than Linux, the only other OS I can seriously recommend would be Windows. I'm not a fan of MacOS, even though it is UNIX-like. Actually, I hate Apple's entire strategy. Sell a product that costs an arm and a leg to purchase, with the cheapest possible build quality, and can only be repaired in-house. Complete nonsense, but I digress!
Now, you
could just find an ISO somewhere, and compare the checksum of that ISO to what Microsoft reports on their website (somewhere), but I'm not going to go into that topic any further. Actually, I thought you were able to just download a certain version of Windows from Microsoft directly, but it wouldn't contain the registration key, so it'd eventually end up gimped. Of course, the registration keys can be found, but again, I won't say where.