How to Fix “Your Computer Was Unable to Start” on Windows 11, 10, 8, 7

When “your computer was unable to start” issue comes up, try these methods offered in this post to fix it effectively.


By Dervish / Updated on August 31, 2023

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Symptom: “Windows unable to start/startup repair is checking for problems”

Hi, I wanted to restart my computer because some programs were running slowly. But when I started up the computer again, it failed, and I was told that I should do a Startup repair. Then I did, but the Startup Repair program says, “your computer was unable to start, and Startup Repair is checking for problems, and it cannot start up normally.


Is there any solution to fix this problem? Thanks for your answer in advance.”

- Question from

Causes: Your Computer was unable to start

Did you ever run into a similar issue? When you need to restart your computer, the Startup program will be automatically launched, and it says “Your computer was unable to start, and Startup Repair is checking your system for problems”. Even if you force it to restart again and again, your computer would be stuck in startup repair loop. How can we solve this problem?

To fix a computer unable to start, we need to figure out what is the cause of it. There are some most common reasons listed below for your reference, then we can find a correct way to fix it.

  • Incorrect update or configuration
  • BDC error
  • MBR corruption
  • File system error

How to fix “your computer was unable to start" on Windows 11/10/8/7

Based on the reasons, you can try the following 4 fixes to one by one until the “your computer was unable to start” issue gets resolved.

Method 1. Enable Safe Mode

In Windows OS, Safe Mode only allows essential programs, applications, and software to start at the boot process. In this way, you can troubleshoot the problem.

If the existing issue does not reappear when your computer is in safe mode, it means the system and basic device settings are not the cause of it. And you can start all the programs one by one on your computer, and find out the reason why your computer was unable to start by using the process of elimination.

1. Restart your computer, and tap “F8” or “Shift + F8” immediately.

2. And go to “Troubleshoot” > “Advanced Option” > “Startup Settings” > “Restart”

3. Then, you will see the “Startup Settings” interface, and choose “Enable Safe Mode”

Safe Mode

✎Note: In different systems, the interface and steps are a little different. For example, in Windows 7, just tap "F8" or "shift + F8" and you will enter "Advanced Boot Options" and choose "Safe Mode".

Method 2. Launch “Last Known Good Configuration”

Last Known Good Configuration is a way of loading the OS configuration that booted computer successfully last time. If the boot issue is caused by driver and software update or installation, the Last Known Good Configuration should be considered.

Step 1. Power on the computer, and tap “F8” + “Shift + F8” when the logo shows up.

Step 2. Navigate to “Repair your computer” > “Troubleshoot” > “Advanced Boot Options”.

Step 3. Use the arrow keys to choose “Last Known Good Configuration”.

Last Known Good Configuration

Method 3. Fix the BCD

BCD(Boot Configuration Data) corruption can be the cause of Windows fails to start. If the Safe Mode and Last Known Good Configuration can’t troubleshoot your problem, you can try to fix the BCD.

▲ Using installation CD

Step 1. Insert a Windows Installation CD, and boot from it.

Step 2. Go “Repair your computer” > “Advanced Options” > “Command Prompt”

Step 3. In the Command Prompt, just type following commands and press Enter to execute them.

  • bootrec.exe /fixmbr

  • bootrec.exe /fixboot

  • bootrec.exe /scanos

  • bootrec.exe /rebuildbcd

Fix Mbr

▲ Fix BCD via AOMEI Partition Assistant

If you don’t have installation CD, you can turn to the reliable and powerful repairing freeware-AOMEI Partition Assistant Standard, which enables you to create a PE bootable USB to start up your computer, and rebuild BCD via its “Rebuild MBR” feature in Windows systems. Here are the steps given below:

Before you do:

  • Attach external drive, like a USB flash drive, a blank CD to your computer.

  • Download AOMEI Partition Assistant to another working computer.

Step 1. Install and open AOMEI Partition Assistant to another computer that can boot up properly. And click “Tools” in the top toolbar, and choose “Make Bootable Media”.

Make Bootable Media

Step 2. Choose a way to make the desired bootable media, and click “Proceed” to start.

Choose Usb Drive



✎Warning: this operation will format the USB flash drive, if it has some data on it, please back up USB firstly.

Step 3. Boot from the PE Bootable USB:

1. Insert the bootable PE USB to the computer that is unable to start. And power on the computer, and press the function key when the first screen appears.

2. Then choose “BIOS setup” and select “Change boot order” to set the USB to the first boot device. and save the change.

Change Boot Order

Step 4. After a whole, you will see the main interface of AOMEI Partition Assistant, and right-click on the system disk, and choose “Rebuild MBR”.

Rebuild System Disk Mbr

Step 5. Choose an MBR type in the small window, and click “OK”.

Choose Mbr Type

Step 6. Then click “Apply” > “Proceed” to start BCD rebuilding.


Method 4. Format system partition and reinstall OS

If the file system of system disk gets corrupted, the system information cannot be recognized, sometimes, the C drive might become RAW. And your computer wouldn’t start. So you can also use AOMEI Partition Assistant to format the C drive to FAT32/NTFS or other file systems and reinstall the system.

Step 1. Create a bootable USB with another computer, and insert it to the computer that unable to start.

Step 2. Boot up the faulty compute with the bootable USB, and when you see the AOMEI Partition Assistant, right-click on the system partition, and choose “Format Partition”.

Format C Drive

Step 2. Choose a file system for the C drive. And click “OK”.

Choose File System

Step 3. At last, click “Apply” > “Proceed” to start the formatting program.


Step 4. When the formatting gets finished, insert an installation CD to reinstall the Windows system.


If your computer was unable to start, you can try these methods according to the cause of it. They can solve most of boot issues. In addition, AOMEI Partition Assistant is a great disk manager, it can also help you to solve other issues, like SSD write-protected. And you can upgrade it to Professional Edition to gain more advanced functions like permanently wipe a hard drive without CD.

Dervish · Staff Editor
Dervish is an English editor of AOMEI Technology; He is delicated to offering users easy and effecitve solutions for issuses related to disks and partitoins. In his spare time, he enjoy wathcning films, playing footable, traveling and so on.