A thing you might want to try if you're a Google Drive user is to pull up Google Drive in a browser on a PC so that you're looking at the unopened Google Photos folder in your Drive on screen, then plug in an MTP USB connection between that PC & your phone, to see if you can transfer the entire Google Photos folder's content from it's Drive storage place to your device's micro SD card by selecting the Google Photos folder in drive & then selecting to download it, then when saving, open up your phone's SD card in the file explorer as the destination (it will be a USB device), then hit the save button on the computer to save all photos you have in the cloud back into a new device (or its SD card). Good luck!