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#21
Ok, you may as well try an in-place upgrade repair install using a 20H2 iso file as Paul Black suggested:
I can't download anything with browsers
Note that 'Mount' will not be available if .iso association is non-default.
If you're unsure which it is there's a tutorial which explains how to find out.
Or you could just use it.. as you have 20H2 there's no chance of upgrading (unless you somehow got an Insider build) and if it's older than 20H2 - which it shouldn't be if recent - then you'll get an error message.
An in-place upgrade repair install normally takes the build back a few minor versions to the last iso build.
I suggest you do this without accepting updates as part of the process.