Usually when we install Windows after installing GNU/Linux, we usually lose the Grub. Which is the best way to recover grub when we lost grub or what are the possible different ways.
You need to boot system using LiveCD of ubuntu and run below command to install grub :
above command will install grub and it also Keep windows bootloader NTLDR into grub , then you can choose any one OS while boot.
Please refer below link for more information :