if you back up your iPhone's data to your iCloud, then you potentially can recover the photos.
the easiest way to do so is with a Mac computer. you can plug your iPhone in, and without resetting it, you can restore from an iCloud backup (tutorial here). you can do the same thing through iTunes if your Mac is old enough to where it doesn't support using Finder yet.
either that or you can reset your iPhone if you don't have a Mac. you reset it, and upon initial setup, you can choose to set up your iPhone to the way it was by selecting an iCloud backup (tutorial here).
you must make sure that you select the correct backup. if you know what time you deleted the photos, select a backup from a time before that. if you select the wrong backup after resetting your phone, you must reset it all over again to switch to an older backup. you can just repeat the process if you select the wrong one on a Mac.