ITunes won't sync music or videos to my iPhone?

I purchased an iPhone 3gs 8gb around December, I've never had any problems with it before except one day recently I downloaded a new video in which I wanted to sync to my phone to show my friends, and then suddenly it wouldn't sync.
I usually have around 7 steps during a sync process, but now I only have three. And they say
1:waiting for sync to start
2: Preparing to sync
3: waiting for changes to be applied.

Then it goes back to the apple logo. What changes do I need to apply?
I even restored my Phone back to its factory settings and now I have no music or videos at all, I hate having such a blank phone!
How can I fix this?

Currently on most updates iTunes and iPhone sofware.

You can abandon iTunes and turn to Wireless Transfer App on App Store.