If your computer sends an error message before Windows loads, the boot sector on the system partition may be corrupted. To understand this problem, you need to know what the boot sector and Master Boot Record are.
The boot sector is a small part of the hard disk startup that created every time you format your drive. It contains codes and data to help the BIOS manage Windows startup process control.
The boot sector also houses a Master Boot Record (MBR) that contains a signature for the disk, partition schedule, and master boot code.
When the PC is turned on, the power-on routine will be managed by the BIOS and then the BIOS will load the master boot code into the PC RAM to submit the next task to the RAM. The master boot code is required to scan the partition table, determine which partition is active, load a copy of the boot sector into RAM, and then submit the task to RAM. This process, called bootstrapping , allows the earliest bits of Windows code to load.
The boot sector can also experience the same problems with any part of your drive such as file loss, files becoming corrupt, and even physical damage. When the boot loader process fails, you will find error messages like this;
- Error loading operating system
- Missing operating system
- Reboot and select the proper boot device
- Invalid partition table
- Bootmgr is missing
- FATAL: No bootable medium found! System halted.
If the above messages appear, your Windows cannot start (BOOTMGR) and you need to use Windows Recovery.
Note: But if your Windows can load Windows but stop partially, it is not a problem with the bootloader. This you need to fix using Safe Mode and may try System Restore to restore your computer.
Boot from Windows Installation Media or Recovery Partition
The first thing you need to do is turn your computer into a Windows Recovery state. Most likely, your computer has a dedicated recovery partition that allows you to enter the state of Windows Recovery without the need for a physical drive.
How is it? Depending on your desktop or laptop PC brand, you will see there is a notice that tells you what key to press to start the recovery process.
What if there is no recovery partition? You can also use a DVD or USB that has a Windows installer in it.
If that is not the case. You may need to download legal Windows 10 or Windows 7 ISO file from Microsoft. As long as you have a valid product key.
Even, if your computer is still OK, it is good to download ready for the recovery drive. You will never know when you may need that.
Back to the Windows recovery process, if you are using a DVD installer, click until you find the Windows installation screen appears. Then, click on “Repair your computer “. For those of you who use a recovery partition or repair disc, the display may be a little different but the next step is the same to restore Windows.
Windows will then take you to a recovery state. On the first page, click on the “Troubleshoot” option.
The Advanced Options page will come up next and will contain the options needed for you to perform your computer recovery.
If you are using Windows 7, the display looks a little different. But the function is more or less the same which gives you the option to perform a recovery.
Repair Startup Automatically
In most cases, you should let Windows try to perform the startup fix automatically. It not only repairs the Master Boot Record or re-creates the boot sector, but it will also find and try to fix other problems on startup. On the Advanced Options page, tap “Startup Repair”.
The next page will show all the operating systems that can be detected on your PC and click on which operating system you want to fix.
Windows will start checking for startup problems and start making repairs.
When the repair process is complete, Windows will let you know if the repairs have been successful or not. Either way, it will give you the option to either restart the PC or return to the Advanced Options page.
If Windows fails to repair your PC automatically, you can try repairing the Master Boot Record or rebuilding the boot sector manually via Command Prompt. Usually, when automatic repair can’t fix the issues, using Command Prompt may not give you the fix. But, you may give it a try.
Steps to be taken after recovery
After you have restored your computer, all you have to do is do chkdsk to ensure the integrity of your file system and hard disk. There is a high probability that these bootloader error problems are caused by physical problems on your hard disk.
Then, you also need to do sfc / scannow to detect and fix any corrupt system files. This step aims to ensure that your files are completely harmless and can detect any problems at an early stage.
