Lost all photos and videos gotten from Airdrop after doing a restore from backup

After I got a new Iphone 6 (Apple exchanged it for a new one because my previous Iphone 6 had a software problem) and did a restore from last backup (my last backup was done the night before) at the store with an Apple employee, all the photos and videos I received through Airdrop in the past months are lost. I don't have them anymore on my cloud or Iphone. How can I get them back? I wish I was informed that those pictures and videos wouldn't be on my cloud or new Iphone. Did this happen to anyone else? Please help me if you know a trick to retrieve all my pics and videos (I got important stuff that I need to get back). Many thanks!