How do i get all of my photos back

Log into the same Apple ID.

Restore your backup.

Enable iCloud Photos if you were previously using that, or wish to start using it.

Restore your iPhone, iPad, or iPod touch from a backup - Apple Support

Set up and use iCloud Photos - Apple Support

Log into iCloud.com go to photos then select the photos you want to download or press select all then click the more button and select download. For more information see. Download iCloud photos and videos - Apple Support

Mambruk wrote:

Log into iCloud.com go to photos then select the photos you want to download or press select all then click the more button and select download. For more information see. Download iCloud photos and videos - Apple Support

This will work as a procedure for archiving photos, though it won’t be the easiest way to get those photos reloaded into a recently-reset iPhone. That’ll be the restore from backup, or re-establishing the connection to iCloud Photos and allow that to re-sync with the iPhone.