Back in January Microsoft encrypted all my hard drives without saying anything. I was playing around with a dual boot yesterday and somehow aggravated Secureboot. So my C: panicked and required a 40 character key to unlock.
Your key is backed up to the Microsoft account associated with your install. Which is considerate to the hackers. (and saved me from a re-install) But if you’ve got an unactivated copy, local account, or don’t know your M$ account credentials, your boned.
Control Panel > System Security > Bitlocker Encryption.
BTW, I was aware that M$ was doing this and even made fun of the effected users. Karma.
This has been happening to people randomly for years. Ysed to get calls about it all the time, and that was pre-covid