As surely many of you have already verified on more than one occasion, when we get ready to work with Windows, it may present some unexpected errors. The failures we are talking about here can be due to a multitude of causes, either due to deterioration of the system itself, or due to some component of the PC.
It is for all this reason that nobody wants that moment to arrive when, when we turn on, the computer returns a black screen to us. It belongs to one’s own BIOS from the computer and tells us that it cannot find the operating system. The first thing this failure causes us is surprise, possibly followed by helplessness.
Reasons why the PC cannot find the operating system
We know or assume the operating system is there on the disk drives. At least this is the situation where our pc it was the last time we turned it off without any problem. therefore, the first thing we do almost automatically when we see this error is to restart the computer. Either using the key combination Ctrl + Shift + Del or with the corresponding button, we turn off and on again.
Once we have carried out this common task of troubleshooting, it could be that the message disappears. But it can also be the case, quite likely that we will see it on the screen again, so we are going to see how to solve it. At first the first thing we have to know is that as the message, the problem is that the operating system cannot be found. From this we can deduce that it is the BIOS that cannot load this system.
Fix Windows Boot Failure
The reasons for all this can be several, hence we can also use various solutions. These reasons can range from a simple configuration error in the BIOS to a more serious problem related to partitions, for example. However, we recommend that before format the pc completely try any of the solutions listed below.
Check the BIOS of the computer
Although we do not have access to the operating system, we can boot the BIOS. Here we will have to check two things, firstly, that the machine recognizes the hard disk. If so, we must also make sure that the drive where we have the system installed, be it Windows or any other, appears as the primary boot drive. Keep in mind that the way to enter the BIOS changes from one maker to another.
Usually by pressing Esc, Del or one of the function keys during the boot process before the system loads as such. In addition, the BIOS menus also vary by computer. In this case we usually have to locate the tab Boot using the keyboard to navigate these and locate the options mentioned above.
Reset BIOS to factory settings
If your machine does not recognize the hard disk there are many possible causes, from a faulty unit, to a damaged one, to a connector or a bad configuration. If we don’t know what happens, the only solution is to try to reset all the BIOS menu to their default values. This is also found between the menus of this, where we see an option at the bottom to configure the default values or reset the BIOS.
On many occasions this is with the F9 key, so then we will be asked for a confirmation about this reset, we accept it and restart the PC.
Fix system boot failures
Something we should know is that Windows relies on three elements to start the computer. These are the Master Boot Record or MBR, the DOS Boot Record or DBR, and the Boot Configuration Database or BCD. Therefore, if any of these registries are damaged or corrupted, it is very likely that the Operating System not found error will appear. To fix these boot elements we have to follow these steps, it is not complicated.
First of all, we need an external drive to install Windows, where we use. the media creation tool Microsoft to create a Windows 10 installation, for example. We download this from the official Microsoft website. Then we just have to follow the steps of the wizard in the program to create the installable unit.
When the bootable drive is ready, we use it to boot the PC, specify the language, keyboard, and time format. On the next screen we select Repair the computer. Next, we go to Troubleshoot / Advanced Options / Command Prompt. In the Command Prompt window we write the three commands that we show you below:
Each command can take several minutes to complete. Once all the processes have finished, we restart the PC to see if it starts normally.
Enable or disable UEFI Secure Boot
Another section that we must take into account is that almost all current computers are sold with the UEFI firmware and the corresponding Secure Boot activated. However, in some cases, this may not work as intended. For example, if Windows is installed in a GUID partition table, you can only boot in UEFI mode. At the same time if Windows 10 is running on MBR disk, it will not be able to boot in UEFI mode.
This is why, if we have the error that the operating system is not found, we can try to enable or disable the UEFI secure boot. This allows us to check if either of the two changes solves it. The adjustments are made in the BIOS menu, normally the option is called Secure Boot and is found in the Security tab of this section.
Activate Windows partition
There is also the possibility that the windows partition is disabled at the time, something we can fix. We achieve this with the native diskpart function that Windows includes. Again we start the PC with a USB installation as we saw in the previous step to start the computer with it.
Then we start the PC, but in this case we go to Repair the computer / Troubleshoot / Advanced options / Command prompt. In the window that appears we will have to type the following commands:
En ese momento aparece una lista con todos los discos conectados a l PC, por lo que anotamos el número de disco que nos interesa, normalmente el mayor. Volvemos a introducir estos nuevos comandos:
[code]select disk NUMERO
This will show us all the partitions of the disk that we have selected and we will see in which partition Windows is installed, noting their number again. To finish, we type:
select volume NUMERO
We reboot the computer to see if the failure that we have told you about, whereby the BIOS does not detect the OS, has finally been resolved.