If the photos are still on your phone, the simplest way would be to wire it up & import to Windows Essentials Photo Gallery, or push them via Dropbox etc.
As far as I'm aware, iCloud only stores the last 30 days or 1000 photos. It doesn't keep them all long-term.
From No, iCloud Isn’t Backing Them All Up: How to Manage Photos on Your iPhone or iPad
Are the photos you take with your iPhone or iPad backed up in case you lose your device? If you’re just relying on iCloud to manage your important memories, your photos may not be backed up at all.
Apple’s iCloud has a photo-syncing feature in the form of “Photo Stream,” but Photo Stream doesn’t actually perform any long-term backups of your photos.
iCloud’s Photo Backup Limitations
Assuming you’ve set up iCloud on your iPhone or iPad, your device is using a feature called “Photo Stream” to automatically upload the photos you take to your iCloud storage and sync them across your devices. Unfortunately, there are some big limitations here.
1000 Photos: Photo Stream only backs up the latest 1000 photos. Do you have 1500 photos in your Camera Roll folder on your phone? If so, only the latest 1000 photos are stored in your iCloud account online. If you don’t have those photos backed up elsewhere, you’ll lose them when you lose your phone. If you have 1000 photos and take one more, the oldest photo will be removed from your iCloud Photo Stream.
30 Days: Apple also states that photos in your Photo Stream will be automatically deleted after 30 days “to give your devices plenty of time to connect and download them.” Some people report photos aren’t deleted after 30 days, but it’s clear you shouldn’t rely on iCloud for more than 30 days of storage.
iCloud Storage Limits: Apple only gives you 5 GB of iCloud storage space for free, and this is shared between backups, documents, and all other iCloud data. This 5 GB can fill up pretty quickly. If your iCloud storage is full and you haven’t purchased any more storage more from Apple, your photos aren’t being backed up.
Videos Aren’t Included: Photo Stream doesn’t include videos, so any videos you take aren’t automatically backed up.
It’s clear that iCloud’s Photo Stream isn’t designed as a long-term way to store your photos, just a convenient way to access recent photos on all your devices before you back them up for real.
See also My Photo Stream FAQ