partitioning - My Hard Drive has been Mysteriously Overwritten by Two Bad Partitions

I have a problem - sometime yesterday, my hard drive appears to have been overwritten by something and then re-partitioned multiple times.

Disk 0 is the affected drive; it used to be my Disk E:, and it stored all my personal files, but it was not my boot drive for Windows 10. I have the most important of these backed up, and with TestDisk I can recover the data from the old partition, but I I'd like to get the whole partition back if possible and prevent this from happening in the future.

I have no idea how this could happen, but I can list off recent things I did to the PC, in this order:

1. 
   

   Switched to Preview or Insider edition of Windows 10, to get Ubuntu bash running on my system.

   
   


2. 
   

   Windows 10 did some kind of system-wide upgrade; I think the Anniversary Edition?

   
   


3. 
   

   I installed Origin and the Battlefield 1 Beta on that drive.

   
   

SMART reports the drive is fine. The change happened at some point while the computer was up and running; the E drive just quietly was repartitioned and is now unreadable to Windows.

How can I go about attempting to repair and/or prevent this from happening to another of my drives? Should I attempt to mount the drive in a liveCD environment that can read linux FSes? I can find the old FS using TestDisk and recover files off of the partition, but because the partition type TestDisk autodetected was "none" I can't seem to restore my old (NTFS) partition.

Please help! Let me know if you need to know anything else about my system or the event.