Try Windows 10 ISO. You can try startup repair through it. It is available for free to download from Microsoft website. Once you do that and get the Windows bootloader up and running, you can use tools like EasyBCD to bring back Ubuntu.
I think if you have Windows 8.1 DVD, that too will have some option for startup repair.
There are many Linux ways of fixing this. But I believe they will be tougher than Windows DVD startup repair.