No boot disk has been detected or hard disk has failed

[TGhosh]

I was trying to change my Legacy BIOS to UEFI. I converted mbr2gpt. However, when I restarted and tried to boot, I get a black screen with the error "No boot disk has been detected or hard disk has failed". I tried changing the boot order but to no avail. I ran the HP PC Hardware Diagnostics UEFI and I got PASSED for both short and extensive checks. 

What can be done now?

[TheOldMan]

Well it seems that you have done some research in the expectation of converting to GPT, or maybe you did that already.

Have a look at this page to see if it helps

https://docs.microsoft.com/en-us/windows/deployment/mbr-to-gpt

If that is not what you had in mind, then if you put BIOS back to legacy, does it see the disk again?

[TGhosh]

Thank you, but right now I'm looking for a way to boot to my windows. On my PC, there is no direct option to switch from UEFI to Legacy. The only option related to 'Boot' on my BIOS is 'Boot order' under 'Storage' menu. I have tried manually disabling UEFI boot sources on there and changing the order but nothing worked. I have also tried booting from Legacy from Boot device menu (F9). When I manually disable Lagacy boot sources, I get the error of "No operating system found".

Is there a solution to this? If yes please tell.

[Paul_Tikkanen]

Hi @TGhosh 

The only solution that I know of would be to reinstall Windows, which will also entail reinstalling your programs and files.

Your PC originally came with FreeDOS.

So, in order to reinstall Windows, you will need to install the version of Windows you have a product key for.

[TheOldMan]

Thanks @Paul_Tikkanen 

I had not considered the system did not come with Windows.  That might also explain the statement " I converted mbr2gpt" if it was not installed from the Microsoft site or media.

[Paul_Tikkanen]

You're very welcome.

I have never been able to use the simple 'mbr2gpt' command on any PC it tried to convert from legacy to UEFI.

I have always had to clean install W10/W11 by booting the installation flash drive from the (U)EFI USB or DVD boot source.

You need to have secure boot disabled in order to boot from anything but the Windows boot manager or hard drive.

At least that is how it works on any of the PC's I have installed Windows on.