Hi!
First, I will answer your questions:
- Is there any other way to find out which Microsoft account a device's recovery key was saved to? There is no way to find this out. Not even Microsoft has access to the encryption key, as it is private information. If anyone other than you had access to it, it would be insecure.
- Is there a way to reach a live agent about account recovery for this? Are you referring to account recovery or BitLocker key recovery? Agents or moderators cannot assist with this, as no one has access to your key, and it is not possible to generate a new one.
- If the key can't be found, is there any way at all to copy my files before resetting Windows?
Without the key, there is no way to unlock the drive and save your files. However, during the reset process, you can choose the option to keep your files; this does not always work, though, as it depends on how BitLocker was activated.
About BitLocker, check all your personal emails. Also check if any Google (Gmail) or other domain emails have the Key linked to them. Emails from other domains can also be Microsoft accounts.
- When you log into Windows or any system application using a different domain account (such as Gmail), Microsoft creates a Microsoft Account for you using your email.
- Go to the website below > Log in with one of your emails > See if the Recovery Key is saved in the Email.
https://account.microsoft.com/
- If you can't find your Recovery Key, log out of the Account and log in to another one.
- Also log in with your Google Account or another domain account that you have used in any Windows application.
- If you get the message that the account was not found, go to the websites below and see if one of them works.
https://myaccount.microsoft.com/
https://mysignins.microsoft.com/
https://azure.microsoft.com/en-ca/account
- Sign in with emails of family members who are with you. Sometimes the Recovery Key may be in one of their emails.