If you don't have the win 10 installer, download the Win 10 media creation tool
and use it to make a USB or DVD (your choice)
change boot order in PC so USB or DVD is first, hdd second
boot from installer
on second screen, after the language choices, choose repair this PC, not install
choose start up repair - this will scan PC and ask for logon info. It might fix your stoppage
were you upgrading when it stuck or just starting for the day?