BitLocker: need a key but I never installed it

Hi all, I have an unusual problem. 3 days ago my hard drive got blocker by BitLocker. It asks for a key in order to unlock my hard drive.

The problem is that I have never installed or set up BitLocker. This is a new laptop and no one had access to it except me. So I am 100% sure that BitLocker was never set up. I bought it via Amazon in Boston 4 months ago.

I checked my Microsoft account but didn't find BitLocker key there (again, because I didn't set it up). I called Dell and they told me I should call Microsoft. I called Microsoft and they told me I should call Dell. It's a closed circle and no one seems to be responsible.

My solution is to re-install Windows but in this case, I will lose all my data (which I don't want to do).

Does Dell community has any recommendations? Did this issue happen in the past? Who could have set up BitLocker encryption on my laptop without providing me with a password?

If I don't recover my data, I consider suing Dell here in Boston.