1. No Boot Sector On Usb Device Driver
2. Usb Devices On My Computer
3. Create A Usb Boot Device

I've got a USB flask drive that I can't seem to boot from. I thought it might be a unetbootin problem (I've occasionally had problems booting from flash drives after using unetbootin) but then I used dd to install the iso file and I get the quick message 'No boot sector on USB device' before the computer jumps right to booting form the HD. The drive works fine as a data storage device. All the files are visible and readable, I just can't boot from it.

'No Boot Sector Found On USB Device' I am trying to set up an external USB drive as a bootable installer for Windows 7 Pro (x64). The drive is a Western Digital My Passport 300GB USB drive. No boot sector on USB device even though I had selected the USB HDD during installation as the destination to install the bootloader. Luckily, starting the system via the Ubuntu installation DVD (which utilised the USB HDD, so it seems only the bootloader was missing on the USB HDD) worked. Boot sector info: Grub2 (v1.99) is installed in the boot sector of sdb1 and looks at sector 629186 of the same hard drive for core.img. Core.img is at this location and looks for. How are you trying to boot from the usb? Are you using F11 to get a boot device menu? Or have you set the usb ahead of the hdd in the bios boot order? Check the your bios settings in the user manual for your ASRock 960GM/U3S3 FX, in particular: '3.4.7 USB Configuration', and the boot order in '3.6 Boot screen'.

I think it's a formatting problem with this flash drive. I've formatted this drive several times. Do I need to leave some blocks empty at the beginning of the drive? Any thoughts?

The 'missing operating system' or 'operating system not found' error message usually appears on a black window when you start Windows computers. It would prevent you from booting Windows. This error is very common for Dell, Acer, Lenovo, HP, and Sony desktops and laptops. You can read on to get error details or skip directly to solutions.

Workable Solutions	Step-by-step Troubleshooting
Fix 1. Check BIOS	Press and hold 'F12/F10' to enter BIOS...Full steps
Fix 2. Reboot from a bootable disk	Press and hold 'F10' and press 'Power'...Full steps
Fix 3. Set BIOS to default settings	Find BIOS and enable the default setup option...Full steps
Fix 4. Rebuild MBR using cmd	Insert the Windows installation CD/DVD...Full steps
Fix 5. Rebuild MBR using software	Boot PC from EaseUS Partition Master ...Full steps
Fix 6. Rebuild MBR for HP	Boor from Windows Operating System Disc...Full steps
Fix 7. Set correct partition active	Boot from EaseUS WinPE bootable disk...Full steps

Causes of Missing Operating System/Operating System Not Found

Generally, when something goes wrong with the BIOS configuration, hard drive health, or the Master Boot Record (MBR), you can't boot the Windows and will see the mentioned two error messages. To be specific, the causes that lead to Operating System Not Found are as follows.

• The basic input/output system (BIOS) does not detect the hard disk
• The hard disk drive is damaged
• Improper/incorrect BIOS settings
• Windows Master Boot Record (MBR) is corrupt/damaged
• An incompatible partition is set as active

Note: If the BIOS fails to detect the operating system, you will receive one of the following error messages, which tells the same problem on different operating system versions.

Error message 1: Missing Operating System

Error message 2: Operating system not found

7 Solutions to Fix Operating System Not Found or Missing

No Boot Sector On Usb Device Driver

After knowing the causes for an operating system not found or missing in Windows, now it's time to apply effective solutions to restore the missing operating system.

Solution 1. Check if the hard drive is detected by BIOS

Step 1: Press and hold 'F12/F10' while pressing the 'Power' button to turn on the PC.

Step 2: Release F12/F10 when the BIOS Setup Utility is displayed.

Step 3: Try to find IDE Primary Master, IDE Primary Slave, IDE Secondary Master, and check whether they can be detected or not.

If no disk is shown or displayed as None/Not Detected, it means that the BIOS doesn't detect the drive and you may select None to Auto. This may solve OS not found error.

If the system disk information is displayed, it means that BIOS can detect the hard drive and you need exit BIOS.

Solution 2. Test hard drive problems

Step 1: Press and hold 'F10' and press the 'Power' button to turn on the PC > Release F10 after the PC screen display you with a test.

Step 2: Use the right arrow to select the 'Tools' menu in the BIOS Setup Utility.

Step 3: Then select 'Hard Drive Self Test' > Press 'Enter' to start the test.

After the test, you'll get two results:

#1. All tests passed

the hard drive is not damaged. You may jump to Solution 3 to reset BIOS to the default state.

#2. The test failed

You should contact your hard disk or computer manufacturer for a replacement as long as these devices are under warranty.

Solution 3. Set BIOS to default settings

Improper settings or incorrect BIOS settings may also cause the issue 'operating system not found' in your PC. You can try to set BIOS to default settings to solve the problem.

Step 1: Restart PC and enter BIOS.

Step 2: Find BIOS and enable the default setup option, including Load Optimal Defaults, Get Default Values, Load Optimized Defaults, Load Setup Defaults, and so on.

Step 3: Press 'F10' to save changes and quit from BIOS.

If this method doesn't work, the MBR disk could be damaged and you may jump to Solution 4 to find the MBR disk repair method.

Solution 4. Repair MBR with the installation CD/DVD

Both wrong operation and virus infection can damage MBR, which locates in the first sector - usually sector 0 of the hard disk. Thus, Windows will not boot. You can try to repair MBR using the Windows installation disk in Command Prompt.

Insert Windows Operating System Disc to the optical (CD/DVD) drive

Step 1: Press the 'Power' button to turn on the PC > Hit 'Enter' when Boot from CD prompt.

Step 2: Press 'R' key in Windows Setup Menu to start the Recovery Console.

Step 3: Type: FIXMBR at the C:> prompt and hit 'Enter'.

Step 4: Press 'Y' key > hit 'Enter' when asked if you want to write a new MBR.

Step 5: Restart PC by pressing the 'Power' button when the MBR completes the writing process.

Usb Devices On My Computer

Solution 5. Rebuild MBR without Windows installation CD/DVD

If you prefer an easier and safer way to rebuild or repair the MBR disk, you may apply third-party partition magic software - EaseUS Partition Master to perform an automatic repair.

Boot your Windows from the WinPE environment you created and start to repair MBR with a few clicks.

Step 1.Create a WinPE bootable disk.

• Download and launch EaseUS Partition Master on a new PC which runs the same system as yours.
• Click 'WinPE Creator' on the toolbar. And select to create the bootable disk on a USB drive. If your computer has a CD/DVD drive, you can also create the bootable disk to CD/DVD.
• Click 'Proceed' to finish the process.

Step 2.Rebuild MBR.

• Connect the bootable USB or CD/DVD to your PC.
• Press 'Del' when you are restarting the computer. Boot your computer from 'Removable Devices' or 'CD-ROM Drive'. And then EaseUS Partition Master will run automatically.
• Right-click the disk whose MBR is damaged. Choose 'Rebuild MBR' to continue.

• Select the type of MBR with the current operating system. Then, click 'OK'.

• Click the 'Execute 1 Operation' button at the top-left corner and click 'Apply' to build the MBR. After that, your computer can boot normally again.

Solution 6. Repair MBR for HP

Solution 4~5 to corrupted MBR repair is applicable to various computer/laptop brands. On top of that, some brands provide customers with inbuilt tools to deal with MBR issues. For example, the Windows Operating System Disc (OSD) provided with HP notebook PC can be used to repair the Master Boot Record.

Follow all steps at https://support.hp.com/us-en/document/c00476274

Create A Usb Boot Device

Solution 7. Set the correct partition active

When Windows is running under Legacy BIOS + MBR mode, the boot partition/system partition should be set as active so that MBR can pass boot right to boot manager and find Windows. If the system partition or boot partition is not set to active, you may encounter the operating system not found issue.

In the same partition tool, create the EaseUS Partition Master bootable USB first, and follow the steps to set the boot partition active:

Step 1. Download and launch EaseUS partition manager software.

Step 2. On the disk map, right-click the desired partition and choose 'Set Active'. The software will automatically execute the operation and create an active partition for you.

Conclusion

All effective solutions to the 'Missing Operating System' or 'Operating system not found' error are carefully presented on this page. You may try any one of the methods to resolve the issue and get a healthy Windows system back and continue using your computer again.