[Shraddha92]

I was trying to change my Legacy BIOS to UEFI. I converted mbr2gpt through command prompt. However, when I restarted and tried to boot, I got 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.

Right now I'm looking for a way to boot to my windows 10. 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.

 

[Couriant]

Try choosing Legacy - hard drive. You may have corrupted the boot and the only recourse is to reinstall windows.

 

[flavallee]

What is the exact serial number(S/N) and exact product number(P/N) on that HP computer?

If Windows 10 was installed and running in it in legacy mode, then you changed it to UEFI mode, it will not boot - as you have already discovered.

I fear you will need to do what was said in post #2.

 

[Macboatmaster]

I suggest you boot the computer from a windows 10 installation media and see if startup repair is available under repair this computer etc.
When you reply and if you need it I will provide more detail