After Ubuntu is installed on a mobile hard drive in win7, it cannot be started independently. How can this problem be solved?

1. Use a USB flash drive in win7 to create a boot disk and install Ubuntu to a mobile hard disk, during Ubuntu installation, the boot loader under win7 is overwritten by default because it is not set to boot the loader to the mobile hard disk. As a result, Windows 7 cannot be started independently. You must insert a mobile hard disk to choose Windows 7 or ubuntu.
2. solution (it is best to back up important data in the Ubuntu system before performing the following operations ):
Use a USB flash drive to create a Windows 7 boot disk or a CD. Unplug the data cable from the mobile hard disk and PC, restart the computer, press F12/F9 to select your win7 boot disk (USB flash disk), and then press F12/F9 on the CD, after a while, go to the win7 installation page and click "Next" to fix your computer.
Next, an interface is displayed, including:
1: Fixed startup-fixed most common startup problems;
2: System Restore-restore the system to the original Restore Point;
3: restore the system image-Restore it with the previously created system image;
4: Windows Memory diagnosis-check whether the computer memory is faulty;
5: command line window-allows you to use command line mode.

"1: Start Repair" and "5: command line window" may be used"
Click the command line window and use the doscommand to switch to your USB flash drive. If my USB flash drive is an I drive letter, run the following code:
I:
CD boot // jump to the boot folder on the USB flash drive
Bootsect/nt60 sys/MBR (bootsect is a new command column tool for Windows Vista/7. When bootsect is used for repair, the parameter/nt60 sys/MBR indicates that the master startup code compatible with bootmgr is applied to sys and the MBR (primary boot mark) is rebuilt ). Sys means to update the master startup code on the system disk used to start Windows. After entering and executing the fix, if successfully updated NTFS filesystem bootcode... Congratulations, restart your computer.

If success does not appear but the system partition was not found, exit the command line tool and click "1: Start Repair" to enable automatic repair for Windows. Then, the system will prompt you to restart, after the reboot, press F12/F9 to start the USB flash drive, and then go to the win7 installation page -- repair your computer -- at this time, a page may pop up, it contains Windows 7 (E :) and so on. Then click Next, select the command line window, and re-enter:
I:
CD boot
Bootsect/nt60 sys/MBR

3. At this step, win7 can be started independently, but Ubuntu on the mobile hard disk cannot be started. If the drive letter file system of ubuntu on the mobile hard disk is ext2/3/4
In Windows, by default, you cannot browse the drive letter installed with Ubuntu on the mobile hard disk. In this case, you need to use the software: ext2read to search for it directly, download it, right-click it, and run it as an administrator, you can browse the files in the Ubuntu system.