Unable to boot linux operating system

window 10 is installed in drive C: and linux mint is installed in drive D:
but at startup only window10 starts where linux mint is not visible to me..

You need some software to permit you to select the disk to boot from when you start up.

Did you choose your boot management software yet?

not yet ! i have no idea of such software
please suggest me some softwares so that i can work on linux

ys! i installed easybcd softaware i click on "add new entry" tab where everything is disabled under linux mode and also under in "edit boot menu tab " it only showing me one window that is window 10

Maybe your Linux disk is not bootable?

My guess is that easybcd does not show the disk because the disk was not formatted / marked as bootable.

See, for example:

fdisk  /dev/sda
Command (m for help): m

Command action
   a   toggle a bootable flag
   b   edit bsd disklabel
   c   toggle the dos compatibility flag
   d   delete a partition
   l   list known partition types
   m   print this menu
   n   add a new partition
   o   create a new empty DOS partition table
   p   print the partition table
   q   quit without saving changes
   s   create a new empty Sun disklabel
   t   change a partition's system id
   u   change display/entry units
   v   verify the partition table
   w   write table to disk and exit
   x   extra functionality (experts only)

Command (m for help): a
Partition number (1-5): 

is it possible from your side to take my system remotely

Your system is running Windows 10; sorry, I have no idea about anything "Windows" anymore.

Maybe @RavinderSingh13 can help you; because he runs Windows on his laptop

Thank you for accepting my connection request.

i installed linux-mint along with window10 but at startup only window10 works
I also fails to add new entry for "linux mint" through easybcd software.

As mentioned before....

You should use a disk utility to insure that the disk partition you want to boot is indeed bootable.