Question Dual boot: main drive no longer bootable

[Starfishpaws]

This morning my dual boot pc (Win 10 & Win 8) decided to stop recognizing the Win 10 drive as a bootable device. If it's first boot device in bios I get an endless loop of restart/BSD error 0xc0000001. If I put the Win 8 drive in first position it boots up and I can see all the files on the Win 10 drive and r/w to it. Also in the bios the Win 8 drive is labeled Windows Boot Manager but the Win 10 drive isn't.
Any help would be very appreciated

 

[JohnBonhamsGhost]

try F8 as the system loads and see what's available in Boot Manager.

if the 10 install is corrupted it still won't be able to load and you'll know you need a restore or reinstall.

 

[rocktalkrock]

Have you tried disconnecting the Win 8 drive and boot with only the Win 10 drive connected?
Have you tried moving the Win 10 drive to a different Sata or M.2 port?

 

[Starfishpaws]

Thanks. I have physically moved and reset the drives and booting with only win 10 brings up the Recovery BSD.
F8 doesn't seem to do anything but both drives are listed in bios and recovery options ->devices.
I have a usb with the Win 10 iso downloaded from MS but I can't seem to boot to it. After searching it sounds like it isn't bootable but I also can't make it bootable from win 8?
Thanks for any thoughts you have

 

[rocktalkrock]

Thanks. I have physically moved and reset the drives and booting with only win 10 brings up the Recovery BSD.
F8 doesn't seem to do anything but both drives are listed in bios and recovery options ->devices.
I have a usb with the Win 10 iso downloaded from MS but I can't seem to boot to it. After searching it sounds like it isn't bootable but I also can't make it bootable from win 8?
Thanks for any thoughts you have

If you can read/write to the Win 10 drive from Windows 8, have you tried checking the health of the Win 10 drive using CrystalDiskInfo?

 

[JohnBonhamsGhost]

F8 doesn't seem to do anything

F8 will bring up the Boot Manager.
it's possible you aren't pressing it at the right time.
just spam it from the time the system is powered on.

 

[Starfishpaws]

Thanks to everyone who offered help. I've fixed the problem but I tried so many things using command prompts and iso files and creating new boot sectors that I'm not actually sure what finally worked. I rebooted for what seemed like the 100th time and the system suddenly was able to repair the Win 10 disk even though it hadn't been able to before.