Q: My macbook air was locked by find my iphone. How do i unlock my macbook air?

Welcome to the Apple Community.

Enter the code you entered when you locked it, if your device used screenlock you may not have needed to enter a code, in which case enter your screenlock.

If your mac first displays a folder icon with a question mark, it cannot find the boot files (OSX).  What you do next depends on which version of OSX you had on the mac.  But whatever, it will involve reformatting the drive and installing OSX.  If you have Time Machine backups, you will be able to restore a backup to the drive, otherwise you've lost all your data.

So tell us which version of OSX the mac had.

Thank you. Saved my sanity.

i just did up to #2, and my problem was resolved.

THis is was after 40 minutes of tech support, mostly just waiting. It took 20 minutes to communicate the issue.

IN a nut-shel, this is what I did. 

Held the power button down to turn off the computer.

Restarted the computer. When the start up sound sounded, I pressed the command and r keys.

I Entered my unlock code

and on the next screen, I entered it again.

Then I regained access to my computer.

I Did not need to go through the scary steps 3 and 4.