Windows 10: How do I get my recovery key when my device does not show up in my Microsoft account?

I had saved my recovery key on a separate USB drive, which unfortunately quitted service without me noticing. Obviously I should have had another backup but I am still hoping for some solution.I tried to get my recovery key via my Microsoft account. But for some reason there shows up no devices linked to my account, although it should have been set up that way.Since I do not have any access to my windows device without that recovery key, I cannot follow the instructions I have read on that topic in this forum.Is there any possibility for me to not reset my PC?I welcome any ideas.

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Recovery of Microsoft account and recovery key

I used a phone number to create a Microsoft account for my windows activation and the recovery key belongs to this account. The number is not active anymore and I also forgot the password. There is no way to get this number back. I need to retrieve recovery key from this account before dropping this account and create a new one with currently using phone number. Tried reaching Microsoft account recovery with available info but response is "Unfortunately, our automated system has determined that the information you provided was not sufficient for us to validate your account ownership". If I try to switch to local account, it says "to back up my recovery key before switching". I am worried if switched to local account without back up, I might lose microsoft account forever and recovery key along with it. Kindly provide suggestions to recover the key.