I have an Ubuntu system on which I installed Windows knowing that I would lose GRUB. Now Windows is installed properly, but while booting I am not able to choose between Ubuntu and Windows. It directly boots to Windows but I can see the Ubuntu partition. How do I restore GRUB?
Boot into Ubuntu using a live-usb (Select try Ubuntu when asked).
Open terminal and install 'boot-repair':
sudo add-apt-repository ppa:yannubuntu/boot-repair sudo apt-get update sudo apt-get install -y boot-repair && boot-repair
and choose the Recommended Repair.