Boot issues

[Willimantic]

Hp Envy (about 5 years old) having boot problems. When I turn it on the screen is black. Text says "Boot Device Not Found. Please install operating system on your hard disk. Hard Disk (3FO)" 

I did the system diagnostics and it passed both tests but the computer still won't work. Unsure what to do to fix this. 

[WAWood]

@Willimantic 

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

In terms of the first, Windows boot files, a way around that is 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.