Solution 1:

I think, you need to fix your grub. For this you have to open Ubuntu. You can use a live Ubuntu in this case.Then

  • install boot repair

    • sudo apt-add-repository ppa:yannubuntu/boot-repair
    • sudo apt-get update
    • sudo apt-get install -y boot-repair
  • open boot repair app :

    • on termianl : boot-repair
    • Select Recommended repair
    • ok for everything
  • then restart pc and remove usb.

Hope you will find your both boot options.