Windows 10: Windows 10 no longer dual boots properly

Okay, I've clearly managed to mess something up, but here goes...

Prior to a couple days ago, my system was setup in a dual boot configuration, with Windows 8.1 (not set as Default, but technically my "primary"), and the Windows 10 Technical Preview (Default) which I used to play around with as a sort of clean work environment. OS's were installed on physically separate drives.

A couple days ago, I successfully updated my 8.1 installation to 10. Dual boot still functioned properly, although this upgrade reset the 8.1-now-10 to Default OS.

Shortly after, I decided to wipe the Technical Preview drive, and do a clean install of the now-released 10, and reset my whole little work environment. After installation was completed, I immediately noticed that no boot menu presented itself, even for a moment. Additionally, in the Advanced System Options/Startup & Recovery, no other OS choices appear.

For some odd reason, there was ONE thing I did differently during this installation though:
Normally, on a clean install, I will delete ALL existing partitions on a given target drive, and allow the setup to recreate them. However, this time -- possibly because the new-ness of 10 had me slightly confused -- I deleted only the primary data partition that contained the Tech Preview install, but left the System Reserved and OEM Reserved partitions.
I'm unsure if this is the source of my troubles or not.

Regardless, as of right now, I'm unable to access my original 10-upgraded installation, and would greatly appreciate some help in getting this restored.

As I'm sitting on a clean install of my 2nd OS, I've no problems with wiping it and trying again, but I thought I'd wait for a little expert advice first.

:)

 

How do I restore dual boot capability after Windows 10 clean install removed it

My computer was dual-boot with Windows 7 boot partitions on two separate drives. After upgrading to Windows 10, the dual boot provision worked fine. However after a clean install of Windows 10, dual-boot capability is no longer available. The boot partition
for the remaining Windows 7 syBistem is intact. Only the dual boot option is gone.

I tried the changing the default operating system under System Properties/Advanced/Startup and Recovery, but the only choice is Windows 10. Windows 7 isn't a option. I'm guessing that the clean Windows 10 install wiped out access to the dual-boot menu.

Thanks.

Bill

 

Windows 10 Upgrade no longer accessable

The machine came with Windows 7 installed. When the upgrade to Windows 10 came out, I installed Windows 10 as a separate boot so I could boot either operating system. The dual boot worked for a while but I haven't checked it recently. I can no longer
see the option for the dual boot.

I will follow up on the links and see where that goes.

Thanks.

 

A screenshot of disk management would help to identify the problem.

 

Although it's probably obvious, Disk 0 is the current Clean 10 install, and Disk 2 is the other 10 upgrade install.

 

No ideas? Anyone?
Short of physically disconnecting Drive 0, I've no idea how to get back to my other OS. (And I'm not keen on the idea of having to install a swappable bay to get around this issue for now.)

 

From what I saw. Disk 0 is your new upgrade to Windows 10 and Disk 2 is the other Windows 10. Disk 1 should be marked as inactive.
From the upgraded Windows 10. Open the Admin Command Prompt and type:
bcdboot E:\Windows

 

Thank you for the response.
Just prior to reading it, I poked around with EasyBCD and -- while not the pretty graphical interface it once was -- was able to add back the option for the upgraded 10. (I was stuck in the clean install.) It booted slow as snot, and for a moment, I thought I was in for a host of other issues, but once it settled, I switched back and forth a couple times to make sure it stuck. All seems well for the moment.
Thank you all for the assist.
Marking as Solved for now. *Smile