Windows 10: BIOS corrupted by update - "An operating system wasn't found"

My Dell Latitude E6540 was interrupted in the last Windows 10 update. Restarting resulted in freezing on Windows Loading Screen. I restored it to an earlier point and it worked until it updated again where it froze on the Windows Loading Screen. I got this refurbished laptop a couple months ago and had created a recovery from the Inspiron 15 5000 series. The BIOS appears to be corrupted/lost "Invalid Partition Table!" has turned into "An operating system wasn't found." I tried the Dell.com website for the BIOS on a USB Flash Drive and it wouldn't download. I tried to use the command prompt option to force the download as the Dell.com website instructed. I have tried to download a copy of Windows 10 and the Dell.com download for the bios on the USB flash drive. Nothing seems to be working. I have tried several different BIOS from different websites.

:)

 

An operating system wasn't found

Hi,

It's odd that you have already performed everything, even a reset, still you're getting the error message "An operating system wasn't found. There's a high possibility that the operating system on your computer is already corrupted. We suggest that you perform
a clean install to resolve this issue. However, since you don't have a backup, expect that everything will be removed on your computer. You may create Windows 10 installation media through this
link. Once done, you may follow the steps on this
link to perform the clean installation of Windows.

We're just here if you need further assistance.

 

an operating system wasn't found

Hi Emanuel,

Welcome to Microsoft Community.

Your question does not contain all the required information needed for us to help you.

In order to help you better, please reply to following questions.

1. May I know the complete error message?

2. Did you make any hardware or software changes prior to this issue?

An operating system wasn't found error means that your computer is not able to find the Operating System on your Hard disk.

I suggest you to follow the steps recommended by Amit Kumar on October 14, 2015
on same issue and check if it resolves the issue.

An operating system wasn't found - Windows 10

Please reply back with complete information on the issue you are facing for further assistance.

Thank you.

 

An operating system wasn't found.

Hi,



Thank you for writing to Microsoft Community Forums.



This issue may occur due to an error in BIOS configuration, a faulty or corrupted hard drive or a corrupted MBR (Master Boot Record) file.





Method 1: Change/Reset BIOS.

I would suggest you to disconnect all external devices (except keyboard and mouse) and change BIOS settings or reset it to default.

Note: Modifying BIOS/ complementary metal oxide semiconductor (CMOS) settings incorrectly can cause serious problems that may prevent your computer from booting properly. Microsoft cannot guarantee that any problems
resulting from the configuring of BIOS/CMOS settings can be solved. Modifications of the settings are at your own risk.

To reset BIOS to defaults, check the user manual of your computer or get in touch with the system manufacturer.

After resetting BIOS, ensure that the hard drive is set as the first boot device.

Save the changes and reboot the computer.



Method 2: Run Windows Automatic Repair.

In most cases, Windows automatic Repair process can fix boot related errors.

To run Windows automatic Repair, please follow the steps mentioned below.

• Boot the computer from the installation media (USB or DVD). If you don’t have a Windows installation media, you can create one by following the steps mentioned in the link:
  
  Create installation media for Windows.
  
• After making language, time and keyboard selections, click on ‘Next’.
  
• Go to Repair your computer->Troubleshoot->Advanced options->Automatic repair.
  
  
  

Wait for the repair operation to complete and see if the computer boots to desktop.



Method 3: Rebuild Boot Configuration Data file.

Boot the computer from the installation media (USB or DVD).

• After making language, time and keyboard selections, click on ‘Next’.
  
• Go to Repair your computer->Troubleshoot->Advanced options->Command Prompt.
  
• Type in bootrec /rebuildbcd and hit enter.
  
• You might be asked if you want to add the file to boot list, please press y.
  
  
  
  Exit command prompt and reboot the computer.
  
  
  
  
  
  Hope it helps.
  
  
  
  Peer Samie
  
  Microsoft Community-Moderator