upgrade window 8 to 10 lead to grub
 

I tried to upgrade from window 8 to 10 lead to grub screen. unable to boot any os any more. I have both linux and window installed on my machine.
anyone can help

thanks

UEFI or legacy boot?

double check that the linux partitions are in fact still there
and that the win10 upgrade did not remove them while making the back up of win8

use your Linux install dvd in "rescue" mode or Gparted live cd