Having tried all day to reinstall grub and trawling the internet I have had no luck. I can no longer boot into ubuntu and have tried boot disk frin yannubuntu but the grub tabs are greyed out. Other methods will not install it on sda1. I have no other os to boot into but have a live usb. Please help
Try this to recover grub:
- Open the live version of Ubuntu (either burn the LiveCD or install the image to a bootable USB device using Startup Disk Creator);
- Open terminal and run
sudo fdisk -lto see where Linux is installed on;
sudo mount /dev/sdxY /mntwhere x is altter and Y a number you have found in the previous step;
sudo grub-install --root-directory=/mnt /dev/sdxto install grub;
sudo update-grubto update grub;
sudo shutdown -r nowto reboot.
In addtion to the other answers, a way with graphical user interface would be to boot from LiveCD or a bootable USB device (putting the live .iso on there with Startup Disk Creator ). Once in the Live session you can install Boot-Repair:
sudo add-apt-repository ppa:yannubuntu/boot-repair \ && sudo apt-get update \ && sudo apt-get install -y boot-repair \ && boot-repair
Then start Boot-Repair from Dash and click "Recommended Repair" to start the repair or take a look at the other options.
Use at your own risk. The usual warnings with non-official repositories apply.
Not sure if this question is still relevant (it seems it's pretty recent).
I ended up here having had the same issue (managed to deleted grub by wiping a harddrive).
I found the following link to be supremely useful:
Looks for section 13 "Reinstalling GRUB 2 from LiveCD".
In my particular case, I had W2K installed on my primary (boot) harddive, and installed ubuntu on a second harddrive later. As a result, grub was installed on the same drive that W2K was on - and allowed me to dual boot between the two.
I decided today that I could get rid of the W2K installation and use the disk space for something else. I stupidly erased the entire drive, including the bootloader...
I physically moved the disks around to ensure that the drive wth the ubuntu installation was the "primary" and used the steps at the link above to re-install grub... Bob's your uncle, I'm back in business.
Hope this helps someone.