Some other possibilities:
If you had iCloud Photo Library turned on, you can use any computer and log in to www.icloud.com and go to the Photos app there to see if you can see the photos. If so you can download them to a computer and if you replace the phone, you can turn iCloud Photo Library on in the new phone and they will sync to it. See: iCloud Photo Library - Apple Support
If you didn't have iCloud Photo Library turned on but possibly did have iCloud backup turned on and have forgotten about it, the backup would have happened automatically while the phone was charging if wi-fi was available. If so, you can restore the entire phone (not just the photos) from iCloud to a replacement iPhone. iCloud: Restore or set up your iOS device from iCloud