well, just reboot and try to use USB to repair this time.
Do as the windows asked.
4. Sometimes, you may also enount errors as follows:
1. sudo add-apt-repository ppa:yannubuntu/boot-repair && sudo apt-get update
Ubuntu yindaoxiufu 引导修复（Boot Repair)
==>> Recommended repair
2. sudo apt-get install -y boot-repair && boot-repair
from: http://blog.csdn.net/piaocoder/article/details/60 589667
3. Then, you can see the followings window: