if you have a spare pc, download this and create a windows install usb or dvd (your choice):
https://www.microsoft.com/en-au/software-download/windows10
change boot order on machine that won't boot to USB or DVD first, hdd second
boot from whatever you made
on the screen after languages choices, select repair this pc,
NOT INSTALL
this will load advanced start up
select troubleshoot
select advanced
select start up repair
this will scan pc and hopefully figure out why it won't start - it will ask for logon details.
If it doesn't work, and it was a system restore you just ran, so no point doing that again... so your next option is boot dvd/usb again, select repair this pc and on next screen choose Reset this pc. You get two options, keep files and settings, or delete everything. either way you need to reinstall all your programs again. I would keep files/settings if I were you... either way, once you choose it restarts pc and reinstalls win 10