I wish I could share good news, but the truth is no one can get you the bitlocker key, including Microsoft staff/support.
You want to think through, what account was used initially to set up the Windows prior to the reset.
IF it is your account, then go check to see if it is here. https://account.microsoft.com/devices/recoverykey
If you set it up with school or work account, it is worth checking here as well https://aka.ms/aadrecoverykey sign in with your work/school email credential in that case.
If the previous Windows was managed via Intune, check with your organization IT support.
I assume you don't remember opting out of not saving it in Microsoft account, and saving it to a local file instead? That's another possibility.
If you can't find it at all, there's really no way to crack it. Bitlocker means business. If it can be cracked, then it means the encryption is not working. Then you do have to format the drive. Sorry.