Restore

If you were not using iCloud photos, you would restore the phone to a backup that was made when the photos were on the device. However, if you have backed up the phone since the photos were deleted, or you were using iCloud photos, they are gone.

Were they backed up somewhere or synced to the cloud?

Did you look in the recently deleted folder?

if you have your pictures and photos in the icloud, you can link your icloud to your iphone to see all your data. But if you forgot save it, I think this is impossible