Here's the instruction for retiring GRUB from live CD
How to Repair, Restore, or Reinstall Grub 2 with a Ubuntu Live CD or USB
Grub 2 typically gets overridden when you install Windows or another Operating System. To make Ubuntu control the boot process, you need Reinstall (Repair/Restore) Grub using a Ubuntu Live CD

Terminal Commands
Mount the partition your Ubuntu Installation is on. If you are not sure which it is, launch GParted (included in the Live CD) and find out. It is usually a EXT4 Partition. Replace the XY with the drive letter, and partition number, for example: sudo mount /dev/sda1 /mnt.

sudo mount /dev/sdXY /mnt
Now bind the directories that grub needs access to to detect other operating systems, like so.

Now we jump into that using chroot.

Now install, check, and update grub.

This time you only need to add the drive letter (usually a) to replace X, for example: grub-install /dev/sda, grub-install –recheck /dev/sda.

grub-install /dev/sdX
grub-install --recheck /dev/sdX



As you can see from my picture, sdb5 is my lost Linux partition so I mounted. Its partition type of Linux Not ext.
when I do sudo mount --bind /dev /mnt/dev && the prompt becomes >> is that OK??
the next command I need to do is sudo mount --bind /dev/pts /mnt/dev/pts && . Can I continue with that at the >> prompt?

After mounting, because my partition is /dev/sdb5 so I need to do grub-install /dev/sdb5? but the instruction says grub-install /dev/sda though.

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Your Windows repair will have replaced the GRUB primary boot loader in the MBR of /dev/sdb with its own. That is what you need to fix, so you do want "grub-install /dev/sdb".

The "&&" is a conditional AND. You use it when you want the next command to run only if the previous command succeeds, and that's most commonly done when you are combining several commands on a single line or in scripts. Using it when manually entering commands on separate lines is unusual. Effectively, all those commands are being combined on one long line, and nothing happens until a command without that trailing "&&" ends that "line". The ">> " prompt indicates that the current command line is not yet complete.

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