Recovery

Did you back up your iPhone on your computer? If yes, and you still have a backup from the time before you deleted the items, you can use this backup to restore from. But you can not restore just parts of the data, the whole phone will be set back to the time, when the backup has been created.

If you sync your photos using iCloud, check the Recently Deleted folder on your device. Deleted photos will be stored in that album for 29 days, if not manually deleted before that point in time.

Have a look at this related article:

If you're missing photos or videos in the Photos app - Apple Support