Depending on what iOS you have, you can check your Recently Deleted folder in the Photos app. This started with iOS 8, so if you have iOS 7 or lower, it won't be there. It also only holds deleted for roughly 30 days, so depending on when you deleted, it may not be there.
Do you not have iCloud back up enabled? It should be enabled by default. Unless you toggled it off. So if you have had your phone plugged in and asleep, there may still be a back up with the photos. You can check at iCloud.com on your computer.