SDL 2021 program disappears

I have or had SDL Trados 2021 installed. I saw there was a new SR but waited to install until I had time to deal with problems. I think it was 16.1.4.4184 but can't go back to look because... When I clicked on "install" it looked as if it was installing - then everything disappeared, including the shortcut on my desktop. I have tried reinstalling Trados from files in my download but without success as it saw either "there is a higher version installed" or "there is another version installed". This has happened before but I made the mistake of assuming it was a one-off so didn't keep notes when I got help to correct the problem.

I have just this minute managed to install SDL 2019 from a download file. Better than nothing but not what I'm looking for.