I have a hard disk booting into Ubuntu 16.04.5 LTS (ext4) that would no longer boot into the GUI.

I used the ubiquitous "Boot-Repair-Disk" on it. It did its stuff and told me all was good. It wasn't; it seems a number of OS critical files went missing after the "Boot-Repair-Disk" process. Now the boot sequence doesn't get past initramfs.

I thought that maybe the Ubuntu 16.04.5 installer would offer a restore option, which is documented, but it doesn't appear when I run it although it recognizes the existing installation.

It'd be nice to get the disk back, so is there any practical way to actually restore a ubuntu installation?

Thanks

Check the file systems booting from a rescue CD or DVD. Possibly the hard disk died and should be replaced.

I'm confident the hard disk is good.

You mean like this:
https://askubuntu.com/questions/9537...n-ubuntu-16-04

?

Why? Anyway, better safe than sorry. Unless you don't care for your data, of course?

Yes.

Do you still have the Ubuntu 16.04 DVD/USB or any other Ubuntu derivative? You could use it to download and run boot repair using the ppa rather than the CD/iso version as the ppa version is more up to date. Use the Create BootInfo Summary option and post the link you get when it finishes so you have some actual information to post here. Boot repair link below.

https://help.ubuntu.com/community/Boot-Repair

Thanks for the feed back and tips, guys, and I think your gods smiled on me this day;

I was able to get to the grub menu and load a previous linux image. It threw a few errors but got me to a terminal mode from where I was able to sort things out and do a dist-upgrade

All good. I have just cloned and image in case there is a disk hardware issue, although I doubt that. It is a relatively new 500GB SDD.

Thanks again.

Cheers