Photos stored on a microSD card are not always in the gallery's trash when you delete them. A recovery scan can still find many of them while the card has not been overwritten.

Recover them on your phone

Keep the card in the phone and stop saving new files to it.
Open DS Recovery and allow Access all files, so the app can read the card.
Start the photo scan. The card is scanned together with the phone storage.
Preview the results and restore the photos you need – preferably to the phone storage, not back to the same card.

Card not showing up?

If Android says the card is damaged or asks you to format it, do not format it. Formatting makes recovery much harder. Try the card in another phone or a card reader first.

Card formatted as internal storage? Then it is encrypted and tied to the phone; photos can only be found while the card is in that same phone.