Reinstall Studio 2019 and get it to run

I did something very stupid... I updated Windows 10 build 18 something to 19 something, latest build. Although I opted for keeping my apps and personal stuff, Windows zealously deleted Studio, MemoQ and God knows what else from the "update". Ok, I reinstall Studio 2019, but Activation will not accept my activation code. On my Studio account the program is set as active, so I decided to deactivate and reactivate, sounds logical, but there's no way to deactivate Studio, the option times out, and when it does not time out it shows some ominous offline deactivation licence. To make long story short...how do I deactivate and reactivate my installation and, more generally, how do I get Studio no to run in demo mode?

BTW, reinstalling MemoQ took about 7 to 8 minutes, no hassle with deactivation/activation or else.