Welcome, my name is Dustin and I will assist you today!
When you plugged the iphone in.. Itunes should have made a backup before it erased your stuff. ( it makes a backup everytime the iphone is connected )
You mentioned a 320 backup, im assuming that was right before the items dissapeared?
Lets try two things, we first need to wipe t he iphone clean, so that its new again.
And then once its clean, lets try restoring from icloud
first, and if that wont work, we can try restoring from that itunes 320 pm backup next.
Heres how to erase the phonehttp://www.pcadvisor.co.uk/how-to/mobile-phone/3296944/how-factory-reset-on-iphone-or-ipad/
And heres how to restore the phone from icloud. http://support.apple.com/kb/ph12521
If you get stuck or run into any issues, let me know.
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