I have Windows and Ubuntu dual boot on my machine. There’s only a boot-able ubuntu live-usb for recovering if I mess them up. This tutorial shows how to restore mbr the Windows bootloader from installed Ubuntu or Ubuntu livecd/usb.
There are two ways to do it:
First of all, boots into Ubuntu live-system and make a update by (launche Terminal to run commands):
sudo apt-get update
Method 1: Install syslinux by command:
sudo apt-get install syslinux
Then use dd command to write mbr:
sudo dd if=/usr/lib/syslinux/mbr.bin of=/dev/sda
Method 2: Install mbr package by command:
sudo apt-get install mbr
Then write mbr to your Windows disk:
sudo install-mbr -i n -p D -t 0 /dev/sda
You may need to change
/dev/sda to where you installed Windows.