I had some trouble with the laptop (an HP x360 13-A113CL) upgrading to Ubuntu 17.04. But something I did along the way gave the Windows an opening to screw me up, and it did. (I have Windows waiting to screw things up, like a Virus you have to pay for and then validate with a license key, sitting there in a dual-boot configuration (unseen and unused since sometime last September). The simplest way to straighten things out was to reinstall Linux. But things keep changing in the hardware-meant-to-run Windows world, so…
The laptop was only half the problem. I was doing some other work on a completely different PC and and wanted watch YouTube videos and look at manuals on the computer next to me. But it was a Windows PC (a Lenovo H535), and it had a weird audio problem where two drivers were contesting over who was in charge of sound output, so I could only get sound with the first video. After fighting that for half an hour, I said, okay, then, time to give this machine a real operating system.
So: here are some notes.
So you’ll probably want to use Ubuntu Boot Repair.