How to restore lost pictures from a media card in my phone?

I have a samsung galaxy s4 and i have had the same memory card for about 6 years. It's been in a few different phones and it has put different pictures in albums. Well i noticed 2 of the albums with some of the very first pictures i put on there are still showing on my phone and the rest of my pictures are gone. Somehow my memory card got almost fully wiped out while being in my phone. I lost some pictures from recent years that are very very important to me. Can someone please tell me how to get them back? Also. I know galaxys have a gallery app and then a photo app that shows all pictures. Mine is no longer on my phone. How could this be? Please help.

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