This is a test of commonsense. Complete the next sentence:

How to find a lost friend 
Make sure you have their name. 
You'll have the best possible chance of finding a long lost friend if you have their full name, especially middle name. A more unusual name will make you search easier, because a name like jimmy john smith is going to turn up a huge number of people when you search.
Remember that your friend might have changed their name. If they're a woman, it is even more likely that she might have changed her last name.