Which photo vault app are you using? You should be able to contact the developer to find out where the files are stored.
As the previous poster noted, if you connect the phone to your PC you may be able to copy the files off of the phone. Then you could put them on the replacement along with the app and hopefully unlock them.
Sent from my rooted, debloated, deodexed Sinclair ZX-80 running CM -0.001 using Tapatalk 2