TO save you time, do you have another computer you can install it on? This won't fix the problem on the current computer of course. But at least you can get on your taxes and get them done before the Oct 15 extension deadline.
I'm not going to hash over what I expect you've already tried with support on the phone. But sometimes it's simple things that get overlooked - such as the date on your computer. Also make sure you are on Windows 10 version 2004. Check that at settings - system - about.
