I am using Windows 7 on Sony Vaio laptop (model number VGN-NR11Z/T). Recently, I tried to start it, but it shows "no operating system found".
I checked the BIOS and "Hard disk: None". I applied the default settings in BIOS and restarted the laptop. But, it didn't improve. So I gave up!
After a few hours, I again checked BIOS and surprisingly it shown my hard disk. So, I start the laptop and was working in it. Suddenly, the laptop went to shut down automatically without any notification and the same message - "no operating system found" - appeared on the screen.
Since then, many times, I have seen hard disk listed in BIOS and can log into my laptop for a few minutes. Also many times, it didn't show any hard disk in BIOS.
Please let me know how to repair my laptop!
System Configuration: Windows / Chrome 51.0.2704.103
You may be facing some connectivity issues. Is this a new hard drive or you have been using it some time? If the laptop is under warranty, contact the seller and ask for guidance.
If the warranty has expired, I would open the laptop and check if the hard drive is properly placed. Remove it and reconnect it back. I strongly recommend you to backup all data the next time you are able to boot. It is really hard to tell you if it is a HDD problem or a laptop problem and, as xpcman said, you may need to consult a technician.