Boot device not found

[Sampath30]

Hp laptop 15seq0500AU is showing Boot device not found and asking to install an operating system on my hard disk ..

[BeemerBiker]

Check to see if there is a hardware problem.

Tap the ESC key after powering on. Tap it once a second after you see the LEDs on the keyboard flash. When you see the startup menu, press F2 to run diagnostics.
If a component fails during the UEFI test then it needs to be replaced.  Do not attempt any updates or restores with a failing drive or memory.

if the UEFI disk and memory test pass then try to boot into windows safe mode

Since Windows cannot start then you need to enter Windows safe mode from outside of Windows

First read this article about safe mode. Skip down to 'Enter safe mode from outside windows. If F11 does not get you into system recovery then try turning the power on and off three or more times in a row.

If startup repair or diagnostics fail, let me know.

I was unable to properly identify your system.

Please provide the Product ID or exact model name for better assistance. Preferably the full product ID including the characters after the # symbol. This code may be needed to find cloud recovery files.