How to recover deleted photos? By mistake, I've accidentally deleted the folder where my phone camera saves the photos; I was trying to delete just a couple of them, but inadvertently the whole folder was selected, and all the pictures that were inside were lost; the folder was residing in the external SD card, not on the phone internal memory.

What is the best way to recover them?
Please don't write anything on your SD card.
Connect it to a PC using card reader or, USB

if you are using windows

use Recuva recovery software

if you are using linux/ ubuntu

use TestDisk app

Both of these software are free.
Hope this helps.