My wife asked me to help her with her Windows laptop one day. She was stuck at the bitlocker prompt and of course didn't remember enabling it or being given a password. I was like, WTF, they're just randomly turning this on by surprise now? LOL
Luckily she was able to eventually get it unlocked by calling MS support.
The bit locker key is saved to the Microsoft account of the user who set up the computer. I was messing with Linux on my new laptop and learned the hard way when it refused to boot back into Windows.
My favorite was finding out that bit locker was enabled on a forced update. The key was saved to the Microsoft account that was used to set up the lappy. Except, I didn't use a Microsoft account because I'm not some tech marionette lemming who needs Gates hand shoved up my ass to tell me how to use my fucking computer. So I used a local account and disabled bitlocker via bios.
Nothing was lost, but it was still a pain in the dick hole.