Why can't get the computer to boot up? I got a message stating " Boot device Not found."

[Pob2]

No one was using the desktop computer. it had to happen when it was running automatic updates. We were about to use it

when we saw the message "Boot Device not found Please install an operating system on your hard disk".

We are using Lan connection. I tried Ctrl alt delete with no result.

It tells me to hit F2-System diagnostics. When I pressed F2 it went to sys. diag. which I ran hard drive check, memory check all was found to pass. I don't know what else to try....

[Prométhée]

Hello
there may be different reason, the computer cannot start because it cannot find the startup information
try what is offered here, read all the links

https://support.hp.com/us-en/document/c01443463

[WAWood]

@Pob2 

The HP link tells you to reinstall Windows and if you do that, you will lose everything currently on your drive.

So, a less destructive approach is to see if you can use another PC to create media to repair the boot files on this PC, because if that works, you will not lose anything in the process.

Windows PCs use two different sets of files to get you to a working desktop.

In terms of the first, Windows boot files, you need to follow the instructions below to create boot media from Macrium Reflect (MR) that can be used to rewrite/repair the boot media on your PC:
1) Download and install Macrium Reflect (MR) from this link on a working PC: http://www.macrium.com/reflectfree.aspx
2) Use the option to create a boot USB stick or CD

That will create MR bootable media. Then, you can boot your PC into WinPE using that media.

Have patience, as that can take a while to start and bring up the screen.

Once the screen is there, select the option to Fix Windows boot problems. It will then search for the OSs installed and list them, Select the one you want to repair and click Next.

It will now do the repairs, listing the things it has done.

When finished, select the option to Restart the PC.

If this worked, the boot repair succeeded and you will have your PC back.

But if it did not, the Windows system files are most likely corrupted and you would have to reinstall Windows from scratch to fix that.

[Prométhée]

It says to test the hard drive to start!

Test the hard drive using HP Hardware Diagnostics

then set the default bios (probably useless but to test all the same

Restore BIOS default settings

then you can try what is indicated again in a link

If the error message indicates 3F0 error or Boot Device Not Found, determine if your computer has Optane memory installed and configured correctly. See HP Consumer Desktop PCs - Boot Device Not Found (3F0) or Automatic Repair Errors

https://h30434.www3.hp.com/t5/Notebook-Boot-and-Lockup/Boot-Device-Not-Found-notebook-pavilion-15-bc...