So is PC working now or you stuck? Did PC offer update or did you find it yourself and run the upgrader?
Do this below if its stuck still - if you not stuick, can still run chkdsk
On another PC, download the
Windows 10 media creation tool and use it to make a win 10 installer on USB << its just a boot disk hopefully
try running chkdsk /r on hdd
boot from installer, on 2nd screen after languages, choose repair this pc, not install
choose troubleshoot
choose advanced
choose command prompt
type
chkdsk /f and press enter. Might take a while.
the only other fix I found that works is a fresh install
is there anything on C drive you want to rescue? try making this on another PC: http://www.howtogeek.com/howto/windows-vista/use-ubuntu-live-cd-to-backup-files-from-your-dead-windows-computer/
change boot order in BIOS so USB is first, hdd second
boot from installer
follow this guide:
http://www.tenforums.com/tutorials/1950-windows-10-clean-install.html
when you reach the screen asking for licence, click "I don't have a key" and win 10 will continue to install and reactivate once finished
On the screen where you choose where to install win 10, if it gives you an error about GPT drives, delete all the partitions on the hdd and press next. If it still gives error, cancel out of the installer and restart PC and start installer again, it will accept next on that screen this time (some PC just need a restart here)