I installed Ubuntu 16.04 with dual boot. Dual boot with Windows 10 seemed to work well. Then I immediately upgraded to Ubuntu 17.04, and I could successfully boot into Ubuntu. However from the first time I decided to reboot from Windows 10, the dual boot menu no longer shows up at startup.
I now started Ubuntu from the USB "Try Ubuntu". I installed boot-repair and you can find the diagnostic here. I haven't actually tried to repair yet, I would like to have some expert advice before proceeding. Thanks!