Help me

[Lele89]

after a reset , my computer says : 

Boot device not found

please install an operating System on your hard disk

hard disk (3F0)

I tried to diagnose by pressing the F2 key, the result says it’s all ok

[WAWood]

@Lele89 

What MIGHT work is rebuilding the boot record on the drive.

You will need to create Boot Media using a working PC.

Macrium Reflect is a free tool that can be used to image and restore PCs, but it also has an option to create Rescue Media (in disk or USB form) that can then be used to bot and/or Repair your PC.

It is available from here: http://www.macrium.com/reflectfree.aspx

What I recommend is the following:
a) Download and install Macrium Reflect (MR)
b) Use the option to create a boot USB stick or CD
c) Boot your PC from the MR media -- it will take a while, so be patient!
d) If needed, select the option to repair the Windows Boot

The PC should now reboot without problems. IF it still has problems, there are other issues at play.