I have a PC with three hard disks. Windows 7 is installed on the first, Ubuntu 14.04 is installed on the third. After I re-booted, it went straight to Windows 7. So I tried explicitly telling my PC to boot using the third hard disk, but that just takes me to the grub rescue prompt.

I followed Scott Severence's instructions here to try and recover. Essentially, I updated grub, reinstalled grub, and then updated it again. After re-booting, absolutely nothing had changed.

So instead I tried using the boot-repair tool. In the past it had failed for me, saying that I had programs running and it could not unmount drives, when I was running nothing. I never figured out how to solve that problem, but it went away when I bought another hard drive and used that for my Ubuntu installation, I don't know why.

In any case, I ran the boot-repair tool and this time it said it was successful. First time for everything right? I re-booted, only to be taken straight to the grub rescue prompt. So I changed my BIOS settings to use the third hard disk for boot start up. That is the same hard drive where I have Ubuntu and grub installed, and the same one that the grub-repair tool told me to use. It still took me straight to the grub rescue prompt. So I went from not being able to boot Ubuntu, to not being able to boot either OS installed on my system. Thanks boot-repair!

Boot repair gave me this URL for future troubleshooting:

http://paste.ubuntu.com/8131669

When I try to boot from the third hard disk, this is my console:

Loading Operating System ...
error: attempt to read or write outside of disk 'hd0'.
Entering rescue mode...
grub rescue> 
grub rescue> set
cmdpath=(hd0)
prefix=(hd0,gpt2)/boot/grub
root=hd0,gpt2
grub rescue> ls
(hd0) (hd0,gpt3) (hd0,gpt2) (hd0,gpt1) (hd1) (hd2) (hd2,gpt2) (hd2,gpt1) (hd3)

Those values look correct to me. I have also experimented with changing some of those values, but 'insmod normal' always throws the same error.

Somebody please tell me how to fix this. I have tried everything, reinstalling grub, and running boot-repair.

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Update: I think the problem might be that the ubuntu installer did not partition my hard disk correctly. I booted from live USB and then launched gparted and looked at how it partitioned things. This is what gparted says:

Partition, File System, Size, Used, Unused, Flags
/dev/sda1 (!), unknown, 1.00 MiB, ---, ---, bios_grub
/dev/sda2, ext4, 2.71 TiB, 47.30 GiB, 2.67 TiB,
/dev/sda3, linux-swap, 16.00 GiB, 0.00 B, 16.00 GiB,

So that first line looks problematic. It is supposed to be the /boot partition. However, it was given only 1 MiB? I am assuming that MiB is actually supposed to mean megabyte, no idea why that 'i' is there. It also says the file system is unknown.

I read the answer by andrew here, and he says he had to do a custom install, explicitly configuring the boot partition. So I think that maybe Ubuntu's installer has a bug in it, where it does not set up the boot partition correctly if you are not installing on the first hard disk in your computer.

I am going to try reinstalling with a custom partition scheme. I read elsewhere (askubuntu won't let me post another link) that I don't even need a /boot partition any more. So instead of following Andrew's instructions ver batim, I'm first going to try having just two partitions: one for /, and another for my 16GB swap space. Both as primary partitions. The first will be formatted as ext4. If that doesn't work, I may try again using /boot.

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So I did my custom install with no /boot partition, and it did not work. When I rebooted, I had an error message saying that some address did not exist. So for the hundredth time, I booted from the live USB, and ran boot-repair. Now I get this message

GPT detected.  Please create a BIOS-Boot partition (>1MB, unformatted filesystem, bios_grub flag).  This can be performed via tools such as Gparted.  Then try again.

I feel like I'm running in circles and nobody will help me.