Re-installing GRUB2

Linux Beginners / Newbie
1

Ubuntu 18.04 LTS/Windows 7 on BIOS computer. 2 HDDs–one Windows7 and one Ubuntu. My Ubuntu 18.04 was an upgrade from 16.04. I have a new HDD that is also screwed up because I used it in this computer. I’m not sure that my computer is capable of using USB sticks to boot.

I’ve had a complete meltdown of my computer. Over the week I’ve been working on it, I’ve learned quite a bit, but not enough.

My Grub2 was accidentally purged during a boot repair repair from Boot-Disk-Repair that uses lubuntu 14.04 for its terminal. I have learned that Grub2 code is installed on every HDD that is used in my system. I have learned that a Windows 7 Pro install disk cannot install a fresh version of Win7 because it can’t use its partitioning capabilitiesbecause the disk in question was initialized for Windows and partitioned on this computer I have learned that GRUB2 cannot find my Ubuntu disk because it isn’t installed. I have learned that my computer cannot run a Ubuntu 18.04 disk made on this computer because of the GRUB2 code that, I’m assuming, was put on it when it was burned, and have therefore learned that I cannot use this computer in its current state to burn anything for booting. I have learned, after a couple of MBR repairs (that placed the bad code on the new HDD) that I can still boot to Window 7. I have also learned that I can run a Ubuntu 16.04 Live Disk (finally) that was burned before the computer got broken.

Now my questions:

  1. The Boot-Disk-Repair Disk has always booted. In its current state it is unable to reinstall GRUB2 because it lacks a repository for 18.04. I have entered apt-get update, and it only shows 6 repositories, none of which contain 18.04, so I declined the update. (I am assuming that these repositories are in RAM at that time). How do I install a repository that Live-Boot-Disk can find to reinstall GRUB2?

  2. Is there any way that I can use the 16.04 Live Disk in this situation?

  3. If Boot-Repair-Disk’s 14.04 lubuntu put the bad GRUB2 code on the new HDD when it partitioned it, how do I restore the new drive so the new Windows 7 will install to it?

  4. If I try to boot from the 18.04 disk, it goes straight to GRUB rescue. Is there a way that I can use that to reinstall GRUB2.?

I do not have access to another computer to burn another 18.04 Live Disk or a fresh Boot-Disk-Repair Disk or a bootable USB Stick (even if my BIOS could use it.)

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Update: I was able to install Ubuntu 16.04 on the new HDD. When I was asked to upgrade to 18.04, I did. With that upgrade, I got sent to grub rescue on reboot, apparently because the MBR still wants to find the old grub partition on a disk that was not installed when the reboot happened. However I had changed its MBR to the bad one earlier.

Should I bother trying to install the Boot-Repair through 16.04?
I do not have Grub2 at all on the new HDD; the old HDDs are disconnected, and I would not have access to GNU Grub.