This has been bugging me for weeks, i tried ignoring it from the back of my mind but i just cant make at peace with it. Why? cuz all my significant data are in my 320GB which is now inaccessible ...

To fix the “Cannot install Windows, BitLocker Drive Encryption is enabled on selected partition” error, suspend BitLocker via Settings or Control Panel, or use your recovery key to unlock the drive.

Your Windows device is likely protected with a passcode — the PIN or password you enter when signing in. For most users, login security prevents unauthorized access ...