macbook air 2013 repairable?

HI I bought a macbook air 2013 for cheap off ebay because it had a flashing folder with a ? on it, so i bought it thinking it would be an easy fix. I ve tried booting recovery but it comes up with a padlock and i obviously have no password and the seller has no idea what password is. Is there any way of getting around this with out taking it to the apple store? I dont have the original purchase receipt so i doubt they would fix it anyway cheers