I am not sure this page will help but it may have information that is pertinent.

https://support.microsoft.com/en-ca/help/4026181/windows-10-find-my-bitlocker-recovery-key

It sounds like a Windows update didn't install correctly and somehow prevented Windows from booting again.  For the encryption, if your laptop meets certain hardware requirements and you associate your Windows login account with your Microsoft account, encryption is automatically enabled.  At that point, in order to access the data without booting Windows, you will need the Recovery Key.  Unfortunately, if you can't get into your Microsoft account in order to retrieve your BitLocker Recovery Key and you didn't back it up anywhere else manually, then your data will be completely inaccessible.  There is a small possibility that a PC technician could get your system to boot again by repairing your small EFI boot partition.  Since that partition is not encrypted, you would not need the Recovery Key in order to attempt repairs, and if the boot problem is caused by that partition, then fixing it would allow Windows to boot again without needing the Recovery Key.  However, if the problem is somewhere else, then your only available option would be to work with Microsoft Support to get access to your account again so that you can access the Recovery Key, which it sounds like you're already doing.  If you can't regain access to your account, then you'll need to wipe your hard drive and start again.

Going forward, you may want to consider using a system image application like Macrium Reflect Free in order to periodically capture full system images.  The main benefit is that a system image backs up your entire hard drive, which means if your PC ever has a problem like this, you would be able to simply restore an earlier full system backup to get it running again.  You can also use it as your main data backup solution if you want, but even if you back up your important data some other way, performing a system image backup every month or so might be useful.  Additionally, if you ever need to change your phone number again, think very carefully about the accounts that use your phone number for additional verification, such as Google, Microsoft, PayPal, Facebook, etc.  You might even want to start making a list of sites that use your phone number for verification, or use a password manager for your passwords in general.  That way, if you ever need to change your phone number again, you can look down the list and do whatever is necessary to make sure you don't lose access to your account when you no longer have that phone number.

And obviously, at the very least back up your important data going forward, either to an external hard drive or to something like OneDrive or Google Drive.  External hard drives are cheap, and Windows File History is very easy to set up in order to get at least basic data backups.