Why does my laptop sometime say operating system not found?

Vista? Well, there’s half your problem. And if the thing hibernates after a certain period of inactivity, that is often problematic as well; hibernation isn’t reliable now, and definitely wasn’t back when Vista was around.

But to answer your question directly, “Operating system not found” generally means that it cannot find a drive that has an OS on it. It’s likely to do that if your hard drive is still asleep and didn’t wake up when the rest of the computer did.

It’s generally indicative of a hard drive issue, regardless of the operating system.

Do you have a USB stick or CD or DVD in the computer?

If so, does error stop when you remove them?

The computer may be looking for an operating system on USB or disc instead of the hard drive.

I started getting these error messages when the hard drive on my laptop was starting to go bad. It was occasional at first, but then started to get more frequent. How old is your laptop?

@2davidc8 I’ve had it for about 5 years, so I’m about due for a new one.

@AshlynM It could well be. My laptop started to behave a lot like that when it was on its last legs. It was 6 years old.

The average lifespan of a laptop is 2–3 years

Beyond 5 years, most computers are obsolete enough that they cannot run the newest software