Pictures in “Photos” App

I uploaded all of my photos onto the photos app a while ago and deleted them from my phone. I left the original setting to where they would be placed. I now would like to access these photos to use for Facebook, etc. yet they are not found in pictures... How do I do this? Also every time I import it does not recognize the pictures on my phone that have already been imported but not deleted off my device,if i allow these to re-imported will I have a bunch of doubles?

Thanks!