Doesn't backing up Iphone data also backs up photo, app document data, music, and be transferred when restored?

I've back upped my Iphone to my compute encrypted but for some reason, i restored it but none of my photos are being transferred as well as my app data, only the app it self being downloaded with no data inside i should of backed up.
Why is this happening?

Added (1). Doesn't backing up Iphone data also backs up photo, app document data, music, and be transferred when restored on Itunes?

Yes, it should backup everything including photos, documents and even login data as it's an encrypted backup. Do you have iCloud photo syncing enabled? It maybe possible that the photos weren't actually on the device but stored in the cloud, check your iCloud to see if they're there. Also check that you're restoring from the correct backup, iTunes can store multiple backups so if you select the wrong one then you won't be restore the correct data

Having just backed up and restored my iPhone, I can tell you it backs up the vast majority of data. It will back up your iTunes purchases but not the music itself. It will re-download any purchases after being restored.

Music you synced from your iTunes library on a PC has to be synced from the PC again.