Refusal to Boot; Fixed Through Recovery; No Idea what Happened

Question

Right now I'm using the latest version of Lubuntu 14, fyi.

Anyhow, I'm not suffering a problem right now, but due to my lack of knowledge on the issue I'm not exactly sure if it's fixed either, and would like some input but I have no idea what the heck happened and how the heck I fixed it.

Yesterday my laptop worked fine all day. Today when I tried booting it up, it refused to do so, as after it got past the BIOs splash screen it would only take me to a black screen where I could type, but none of the typing seemed to do anything.

Rebooting did nothing, so after awhile, purely through trial and error, I managed to get the computer into recovery mode and with an educated guess I selected the option for it to repair broken packages.

During the repair it tossed out tons of code I couldn't comprehend, such as SRST failed (errna=-16), and eventually it got to the log-in screen, where I got through and everything was fine.

However, lacking a proper diagnosis I have no idea what was wrong in the first place. It was saying something about a new GRUB (...?), so my guess is the last time I did a sudo apt-get update, it installed a dysfunctional update to the bootloader and messed everything up.

In this case, how can I find out what went wrong, and prevent it from happening again, if possible?

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Edit

Even with another round of updates and an attempt to fix matters through recovery mode, it's still happening. This time around I took more careful note of what went on:

1.) I turn the computer on, and after a long pause it takes me to a black screen where I can type, but none of the inputs do anything.

2.) Forced restart.

3.) The second time I boot up something different happens: I'm taken to a screen that states it's "GNU GRUB version 2.02^beta2-9".

4.) I select advanced Ubuntu options from there.

5.) I select to boot in recovery mode.

6.) I select to fix broken packages (which I found doesn't do anything).

7.) Finally, I select to do a normal boot of Ubuntu, which then takes me to the usual log-in screen where everything is fine.

So in short, my comptuer won't boot up normally. I have to take these steps through GRUB to boot up via the recovery mode selection menu, which doesn't make sense to me.

And again, I haven't been doing any tinkering with my system aside from the usual sudo apt-get update, so I suspect I downloaded something corrupt.

So what should I do?

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Edit II

I tried Boot Repair, and that that didn't work either. Here's the URL it gave me: http://paste.ubuntu.com/8496242

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Edit III

Did Boot Repair again, and this time it spat out an entirely different code. http://paste.ubuntu.com/8503260

Answer 1

This seems like your GRUB config (/boot/grub/grub.cfg) file was removed, corrupted, or misconfigured.

Generally, powering on your computer would do it's initialization and then load GRUB from the boot sector of your hard disk, and that would then load the GRUB configuration which tells it where to find your initial RAM disk on your drive.

This is usually loaded, which then reads your Linux install and boots normally.

With a corrupted or missing GRUB file, this chain breaks which tends to result in a simple black screen with

boot:

Recovery has a few options here.

You could manually pass options to GRUB at this stage, telling it where your initial RAM disk is.

Recovery mode (which you used) loads Linux from a CD and will then probe your disk and attempt to intelligently build a GRUB config for you. If detected, it will also install GRUB to the disks boot loader.

This process can be done manually using update-grub or grub-install, which can come in handy in situations where an update breaks for some reason and you can tell that you won't come back without handling GRUB. In this case, those two tools can be used to essentially do the same thing that Recovery Mode would do, but on your system that's already booted and running.