pin code

If you can't remember your passcode and you haven't backed up, you are going to have to erase the phone using your phone with iTunes, following the directions in this link --> If you forgot the passcode on your iPhone, or your iPhone is disabled - Apple Support

Since you haven't backed up your iPhone, you are going to lose your data.

You have to have either synced photos with iCloud, or have backed up the phone to either iCloud or your computer. If either was true, you can restore the photos from iCloud or your phone from backup after you've erased your phone. You don't have to backup with iCloud, just have synced photos with iCloud. If you didn't backup up, nor sync with iCloud, there is no way to save your photos. The time to worry about not losing data is before something like this happens. Sorry.