I'm trying to install Ubuntu 14.04 from live USB beside windows 10; but there is no grub and it boots directly to windows. I already did everything suggested in other questions but no luck. I retried the install with and without /boot partition, did the mount thing, but still no sign of grub. The last things I tried were these:

sudo grub-install --target=i386-pc --force /dev/sda7

sudo grub-install --target=i386-pc --force /dev/sda4

sudo mount /dev/sda7 /mnt

sudo grub-install --root-directory=/mnt/ --force /dev/sda

sudo mount /dev/sda4 /mnt

sudo grub-install --root-directory=/mnt/ --force /dev/sda

it shows a warning message as:

Embedding is not possible. GRUB can only be installed in this setup
by using blocklists. However, blocklists are UNRELIABLE and their use
is discouraged.

and says Installation is finished; but when I restart, there is still no grub.
my partitions are:

sda7 --> boot

sda6 --> home

sda5 --> swap

sda4 --> /

sda2 --> C:

sda1 --> windows boot manager (efi)