Help rebooting/restarting

[Gee42]

I turned my computer on and its saying operating system not found . I tried to restart it ,nothing didnt work . I have a presario cq57 and my product number is A7A60UA

[WAWood]

@Gee42 

How old is the laptop -- 5 years or more?

Asking because if it is that old, most likely, the hard drive is failing, that will cause filesystem corruption, and that will prevent it from being able to boot.

To check the drive you have to follow these steps:
1) Press Esc key repeatedly, several times a second, while rebooting the laptop. Do NOT hold the key down, just press it over and over.
2) Eventually, you will see an HP Startup Menu -- that will look similar to the image below ...

3) press the Function key for testing the hard drive (usually F2) and let it run.

Please report back the test results.