HP Pavilion All-in-One - 27-r014 boot device not found

[Cbm2306]

HP Pavilion All-in-One - 27-r014 has a black screen with a red box that says the boot device not found then goes to black screen with blue box that says to please install an operating system on hard disk. This happened out of nowhere and I cannot get it to turn on regularly again or work. 

[VH2000]

Did you check if Legacy Mode is enabled in the BIOS?

Try that first!

It is just a Boot Failure and there is no reason to worry about! 

[Cbm2306]

Legacy boot sources says disabled. A friend of mine said that Windows crashed and it needs to be reinstalled? My only problem is, if this is the case, how do I install it when I can't get past this screen to download it on a browser? 

[Cbm2306]

I enabled the legacy boot and it made me disable the secure boot... now upon restart it shows a black screen and says Error: no boot disk has been detected or the disk has failed. 

[VH2000]

OK, when you run in BIOS-Mode you need MBR-Drives and when you run in UEFI-Mode you need GPT-Drives.

For both system you have a different repair procedure.

So you have to download the "Media Creation Tool" from Microsoft and prepare an USB-Stick. It is needed to boot the machine and to repair the bootmanager.

So when you boot from USB and the setup begins type Shift + F10

this opens the command prompt. Then type:

diskpart

list disk

sel disk 0

list par 

make a screenshot and post the result

then type 

exit

exit

and stop the Installation