Boot-Repair is a simple tool to repair frequent boot issues you may encounter in Ubuntu like when you can’t boot Ubuntu after installing Windows or another Linux distribution, or when you can’t boot Windows after installing Ubuntu, or when GRUB is not displayed anymore, some upgrade breaks GRUB, etc.
Boot-Repair lets you fix these issues with a simple click, which (generally reinstalls GRUB and) restores access to the operating systems you had installed before the issue.
Boot-Repair is a free software, licensed under GNU-GPL. Boot-Repair should be soon included in Ubuntu official repositories, until then use it at your own risks.
1. Boot to LiveCD
2. Connect to Internet
3. Open terminal
4. Give command below
sudo add-apt-repository ppa:yannubuntu/boot-repair && sudo apt-get update
5. Then give command below.
sudo apt-get install -y boot-repair && boot-repair