ALL the photos in my iCloud gone?

Instead of backing my 1, 500 pics up to the computer when I sent my iPhone 4 to be repaired, i backed them up to iCloud. Upon getting my phone back I restored from the most recent iCloud backup. I got everything back, apps, music, background. Everything. Except my photos. It said they backed up but I can't find them and they didn't sync over. Any suggestions?

Though iPhone uses quite a different storage mechanism, still you can recover deleted or lost data (such as text messages, contacts, photos etc) with a third party specific iPhone data recovery software called Tenorshare iTunes Data Recovery. I used it to recover deleted photos from iPhone 4s and it worked.
Here is a tutorial to guide you recover photos from iPhone after you lost or deleted them:
https://www.any-data-recovery.com/topics/mobile-devices/iphone-photo-recovery.html

Hope I helps!