Boot Device Not found

[BabyPink62]

Umm... When I start my device it goes straight to “HP PC Hardware Diagnostics UEFI” . I exit it and it tries to load then shows:

BootDevice Not Found

Please install an operating system on your hard disk. 

Hard Disk – (3F0)

F2 System Diagnostics....

So I go back to system diagnostics and  try a quick hard drive check because someone told me to.

After the hard drive check it shows:

SMART Check:  NOT INSTALLED

Short DSI:  NOT INSTALLED.

So I try an extensive check and it shows the same thing. I honestly don't know what to do 😭😭 and I don't want to loose any important file or document.

Please help.

[BastianW]

Just out of the blue ... try switching to the legacy BIOS mode instead UEFI (see here, but you need to perform it the other side arround).