Is it asking for the BitLocker recovery key?
Was your D drive used to be a system drive taken from another computer?
Or has it been with this computer from the very beginning?
The most important step is to recall what the account was used to set up the computer when this drive was initially used.
Once you identify the account, sign in here to look https://account.microsoft.com/devices/recoverykey
If you set it up with a school or work account, it is worth checking here as well https://aka.ms/aadrecoverykey sign in with your work/school email credentials in that case.
I assume you don't remember opting out of not saving it in your 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 go around it.The drive has to be formatted in order to use it again.