Windows 10: Update to Windows 10 caused unformatted partition?

Hi, I just updated from Win 8.1 to Win 10. Seemed to have worked as it should. But I discoverd I cannot acces my D: partition anymore; I get an notification saying the drive is unreadable and has to be formatted. The partition is located on my Main SDD, together (obviously) with my C: boot partition, which is working fine.
It is not a big loss at itself (D: is only used to install programms), but it's annoying and also quite disturbing...

Anyone got a clue what's going on here?

:)

 

Microsoft wants to know - Anyone seeing issues with the April updates KB3147461 and KB3147458?

My recent effort to install Windows 10 to my win 7 PC ended in disaster..

It appears that the Windows 10 install (original) did something to the C drive causing a large portion of it to go RAW in an unformatted partition. All of a sudden, the C drive only has 1.7 GB free space
while the unformatted partition has the remaining 100 GB. It basically removed most of the C volume and started another partition, “E”. Have no idea what files I have lost.

Any fix on how to get the new partition merged into the C drive in a usable manner so I can at least recover the space?

 

Win 10 home a Win 10 Pro