Windows 10 will not boot from HDD anymore

[fevike]

My Dell Inspiron will not boot back into Windows 10. This happened when I tried to boot Debian from a USB and I believe the boot manager was switched to the USB versus it being on the native HDD. The HDD is still recognized by the computer but it is impossible to actually boot back into it. The Debian installation did not complete as there was some error with the network so it could not get all of the files for the installation.
To do this I put the Debian iso image on a USB and then switched the boot mode into Legacy mode in order to have the option to boot from a USB. Doing this something happened and now I cannot boot back into Windows 10. Let me know if you need more information.

Thanks,
Kevin

 

[Colif]

try switching the boot method back from legacy to UEFI and win 10 should boot fine.

Win 10 uses UEFI boot method, it cannot boot if set to legacy
Win 10 uses GPT partition format which matches UEFI boot. whereas Debian obviously matched MBR partition format that uses Legacy.

 

[fevike]

try switching the boot method back from legacy to UEFI and win 10 should boot fine.

Win 10 uses UEFI boot method, it cannot boot if set to legacy
Win 10 uses GPT partition format which matches UEFI boot. whereas Debian obviously matched MBR partition format that uses Legacy.

When I switch the boot method back to UEFI Secure the computer turns on saying "No bootable devices".

Using Diskpart from a Windows Recovery USB I can see that the partition is Logical therefore not bootable.

 

[SuperSoph_WD]

Welcome to Tom's Hardware, @fevike!

I'd recommend you check if you will be able to repair the boot sector (rebuild the MBR) on the HDD through the Windows Recovery disk/USB. If you have any important data on the HDD, I'd advise you to plug the drive in another system (as a secondary HDD) and check if you will be able to access and back up your files. This way, you will avoid any potential data loss. Afterwards, plug it back in your system and attempt to re-install Windows from scratch.

Hope it helps. Keep us posted with the troubleshooting!
SuperSoph_WD