Case: Windows 7 boot device not found error
“Urgent help! I have a Dell Inspiron laptop with Windows 7 installed and it has been running very well. However, suddenly when I start it, the screen displays” Unable to find boot device – please install operating system on the hard drive “and” No Boot Device Found “prompts.”. Then, I pressed F1 to restart my computer, but the message still appeared. What should I do if my computer cannot find the startup device? How can I fix the error message No Boot Device in my computer? Any suggestions would be greatly appreciated!
Error: Unable to find startup device
The reason for Windows 7/8/10 “boot device hard disk 3F0 not found”
When starting Windows 11/10/8/7, errors such as “No Boot Device Found” and “No Boot Device Hard Disk 3F0 Found” may occur due to the following reasons:
Boot from a disk that does not contain an operating system.
The MBR or boot sector on the bootable disk is damaged.
Physical damage to the bootable disk
The computer has been infected with a virus.
5 methods to complete No Boot Device repair
After understanding the possible reasons why the boot device cannot be found, let’s take a look at how to use effective methods to fix the problem of No Boot Device.
✔ Fix 1 Check the startup sequence and reset the BIOS settings to default values
To ensure that you boot from the correct bootable hard drive, you can press certain keys to enter the BIOS interface during restart to check the boot sequence. Please press “+” or “-” to set the bootable hard drive as the priority boot option. Afterwards, save the changes and restart the computer to see if the “No Boot Device Found” error disappears. If the error persists, please try resetting the BIOS to the default settings by following these steps:
- Turn off the computer and wait for a period of time.
- Restart the computer and press a key such as F12 to enter the BIOS settings menu.
- In the BIOS settings interface, press a key to select and load the default BIOS settings.
- Save the changes and exit, followed the prompts to restart the computer.
✎ Note: If you are unsure of the method to enter BIOS, you can refer to your computer’s user manual.
✔ Fix 2 Perform a hard reset
If you still encounter an error where the boot device cannot be found, you can try performing a hard reset to complete the No Boot Device repair. Here are the detailed steps:
- Turn off the computer. Remove external devices from the computer.
- Remove the AC adapter and battery from the computer.
- Press and hold the power button for about 15 seconds to drain the remaining energy of the computer.
- Replace the battery and plug the AC adapter into the computer.
- Turn on the computer and check if it starts up properly.
✔ Fix 3 Run startup repair using the Windows installation CD
To automatically fix the error “boot device hard disk 3F0 not found”, you can use Windows boot repair. Please refer to the following steps:
- Insert your Windows installation CD into your computer and start it from there.
In the “Install Now” screen, click “Repair Your Computer”.
- In the system recovery options window, select “Start Repair”.
✔ Fix 4 Run the Bootrec command using a Windows bootable disk
If startup repair cannot resolve the error, you can try running the Bootrec command to repair MBR and boot sectors by following these steps:
- Start the computer from the Windows bootable disk and select “Command Prompt” in the “System Recovery Options” window.
- In the command prompt window, enter the following command line and press “Enter” after each command line.
Bootrec/fixmbr
Bootrec/fixboot
Bootrec/scanos
Bootrec/rebuildbcd
Bootrec command to fix MBR
- Exit the command prompt interface and restart the computer.
✔ Fix 5 Repairing damaged MBR does not require a Windows installation CD
If the MBR of your system hard drive is damaged and you do not have a Windows installation CD, you can seek help from a third-party free utility – Aomei Partition Assistant Professional Edition. It has the ability to create bootable media and rebuild MBR. Therefore, you can use it to create portable bootable devices. Then, start the Windows 7 computer from the created bootable media and rebuild the MBR.
To rebuild a damaged MBR, you need to first go to the download center or click the button to download the Aomei Partition Assistant Professional Edition and install it before enabling it. Refer to the detailed steps provided in the following text for operation.
Free download of professional version
Win 11/10/8.1/8/7/XP
- Connect the USB drive to the work computer. Start the software, select “Create Startup CD” on the homepage, and follow the wizard to continue.
Creating a bootable disk
- After successfully creating a bootable USB drive, plug it into the computer with the “boot device not found” error and start it from there.
- You will see the main interface of the Aomei Partition Assistant Professional Edition. Right click on the system hard drive and select “Rebuild MBR”.
Rebuild MBR
- In the pop-up window, select the MBR type of the current operating system.
Choose the MBR type for the operating system
- Return to the main interface, click “Submit” and select “Execute” for this task.
