No bootable device -- insert boot disk and press any key

[iamzubair]

I had windows 10 which was working correctly then I installed ubuntu 18.04.3 , dualboot. When ubuntu's installation completed and it asked to restart the computer after that I'm receiving No bootable device -- insert boot disk and press any key. Guide with this so I can use both windows and ubuntu. I've also data saved in windows which I don't want to losss.

Please help me with this. 

[Lil_Boy_Blue]

Hi

If you know what you did, like install Ubuntu in Legacy Mode, with Windows set in Secure Boot, then toggling the options may solve, temporarily, the situation.

ESC and F9 to select the boot device.

Have you got 2 boot managers installed?  Grub and MS?

If the boot mangers are listed Alphabetically

Ubuntu comes before Windows, so I re-arrange mine to suit.

If in doubt please ask.

[iamzubair]

These are my boot device option. 

When I choose the first option "OS boot..." it says selected boot device failed. Last one "Notebook drive..." returns me to same black screen which says "No bootable device....". However middle one option "Boot from EFI" lead me to ubuntu, after few more steps. 

below picture is of system configuration.

These are default didn't touch them before installing ubuntu.

[Lil_Boy_Blue]

Hi

Well I would have expected W10 to be Secure Boot / GPT when installed.

Secure Boot now seems to be disabled.

You may be able to boot from a UEFI file if you know what the Windows one is.

Try and enable Secure Boot, and then if that works, consider keeping Secure Boot and installing Ubuntu as a Secure Boot OS.

If in doubt please ask.

[iamzubair]

Windows doesn't start. If there is another way please guide me. Else properly guide me how to dualboot W10 with ubuntu.

And what I do so that my data which is in windows remain unaffected. 

[Lil_Boy_Blue]

Hi

I cannot know if Secure Boot was ON before Ubuntu was installed.

But if you cannot/do not tell me the steps you are taking then my answers are pointless.

Try a live Ubuntu, try and ensure the Windows partition is viewable in Gparted or similar.

[iamzubair]

Secure boot was disabled. Now I enabled to run windows through uefi as per your prescription. But this doesn't work. 

[Lil_Boy_Blue]

Try the Live Ubuntu.