Why did downloading WP8.1 remove my camera, photos and contacts and HOW do i restore them?

I downloaded the Windows Phone 8.1 update on my Nokia Lumia 828 phone 1 week ago (after being VERY happy with WP8.0 for 2 years). The update removed my camera function and pictures. After a factory reset (which restored the camera but not photos), i powered the phone off. The next morning I turned my phone on and ALL my contact are gone. I can't import them from my Hotmail or aol accounts. I seem to have NO contacts stored locally or on my sim card (why?). HOW DO I GET MY CONTACTS BACK? THIS IS DEVASTATING.

That stuff should be backed up to the cloud. Pictures, contacts, sms, music all of it.

Contacts should be automatically backed up and synced with the Hotmail account you use for the phone
Check your email and account setting. Sounds like a sync failure there.

It sounds like you didn't link the phone to an MS account and you have no cloud backups.

Important lesson learnt - Backup your data before upgrading.