Hello my name is***** am sorry you have encountered this kind of problem. Have you ran the system diagnostics yet to test the hard drive for a malfunction yet?
Ok so it is saying boot device not found this means either the connection to the hard drive has physically came loose or the hard drive is sadly malfunctioned and would need to be replaced. Have you tried disconnecting and then reconnecting the hard drive?
To answer that what is the make and the model of this computer? I mean just disconnect the data cable and reconnect it to the hard drive.
Is this a desktop computer? If it is you would need to open the side panel to get to the inside.
I see, ok on the bottom of the machine I will need an exact model number please so I don't give you the wrong instruction.
It won't me on a sticker it will be righting that says model number or model no I am going to have to take an educated guess in this case if you can't locate it. On the bottom of the machine there should be an access door or doors on the bottom of the machine you would need to open them and locate the metal square device which would be the hard drive. You would need to remove the hard drive to disconnect it since this is a laptop. If you don't feel like you can do this task you would need to have it taken in and a computer tech for example from geek squad could remove an reseat the hard drive even test it however if I am correct the hard drive would probably need to be replaced and the recovery program would needed to be ordered from hp so everything can be reinstalled onto the new hard drive.
If reseating fails of course it would mean you would need a new hard drive. If you have more questions please let me know if you need further assistance I am right here just ask. If you don't have further question please leave positive feedback using the rating system it's how we are compensated for our time and information.