I accidentally deleted a partition and my system won't boot

Question

I deleted /dev/sda3, and now my system won't boot. I tried to use boot repair; but, it shows me an error message that says

GPT detected. Please create a BIOS-Boot partition

I created one but it doesn't work.

The image above shows the /dev/sda3 partition before it was deleted

This is what it shows now (@Pilot6)

Answer 1

You moved the first sector of your Ubuntu boot partition. That is why the loader does not know where to find it.

This can be easily fixed.

1. Boot from a LiveUSB.

2. Mount you Ubuntu partition to /mnt. I see that you have done that already. But in case you boot again run:

   sudo mount /dev/sda8 /mnt
   sudo mount --bind /dev /mnt/dev
   sudo mount --bind /proc /mnt/proc
   sudo mount --bind /sys  /mnt/sys
   

3. Then chroot and update grub:

   sudo chroot /mnt
   sudo update-grub
   exit
   

4. Reboot to Ubuntu a normal way.

You can also try Boot repair. But you need to know that your Ubuntu partition is sda8 and the EFI partition is sda6.

Answer 2

Try to install grub again, run these commands in terminal.

sudo grub-install /dev/sda

then run

sudo update-grub

Then follow Pilot6 answer.