Just to clarify beforehand, I'm no Windows expert so don't expect a miracle with me
First of all, are you able to access the bios menu? You should be able to. If you can, follow these steps.
1. Restart your computer
2. Quickly access the bios menu during the loading screen, (F12, Del, etc.)
3. Go to options/settings and change the boot order and place the DVD drive on top or a USB.
4. Save and exit.
5. It should boot you into the order you changed, if not, click F12 and select what do you want to boot into.
6. And that should be it for the most part.
If you can, try to install W10 unto a USB, it seems to be the usual way to go.
If you want, you can also run a small Linux from a usb to retrieve your files. I recommend Tiny-Core, its light, and fast.