Recover photos from Google Photos cache
You're best option is to try recovery software such as Recuva or EaseUS Data Recovery on one on the SD cards which once contained the deleted photos. The chances of recovering your data this way are slim, as even just a few missing kilobytes can corrupt whole photos and videos.

Android stores cached images in the following locations:


  /sdcard/DCIM/.thumbnails
  /data/data/com.google.android.apps.photos


If you're not rooted, then refer to this guide on how to use ADB to pull the data from the Google Photos application.

If all else fails, then your last two options would be to try contacting Google Support to see if they still have the files on their servers. Hardware data recovery could restore your photos at a price.