How do I recover my Ubuntu partition?

[Ralf Mardorf]

> On 07 Feb 2017, at 14:26, s_s_shahin at fastmail.fm wrote:
> 
> I divided my hard drive into 3 partitions, 1 Ubuntu 16.04, 2 Windoz and
> was booting Ubuntu day in and day out no problem until I wanted to try
> one of the Windoz.

If this should be correct running

sudo mount /dev/sda1
....................................

Oops, this should read

sudo mount /dev/sda1 /mnt

sudo grub-install --boot-directory=/mnt/boot /dev/sda

likely would fix the issue. But I suspect that Ubuntu is not on sda1, it more likely is on another partition. IOW 1 Ubuntu partition not necessarily is the first partition. However, simply use the live media and run

sudo parted -l

copy and paste the text, so no screenshot is required.