*. First of all Enable Timeline Feature in your Facebook Account .
*. Now open your profile and click on the year in which you
want see the people who unfriended you.
*. Scroll down the cursor till you find Friends column where you wil see list of new friends you made in that particular year. You can see I Made 3 New friends .
*. Click on it and all your friends will be shown in a new pop-up window and if you find Add as Friend option next to any person it means he has un-friended you.
You can check all the years one by one to find out how many of
your friends have un-friended you.
Click hear How to enable Facebook Timeline