MacBook Pro 2012 Model A1278 Flashing questionmark file
Sounds like the drive is dying.
Get it out of the machine &amp; stop trying to boot from it. 

Your best chance of recovery, assuming you don't have any backup, is to attach it to another machine in a USB enclosure &amp; use a recovery utility to rescue it to a separate drive. 

The more you mess with it, the smaller your chances get.