i have upgraded my iphone 4 with the latest upgrade and now i cannot sync with my computer

What kind of computer are you using?

What version of iTunes is it? i.e. 10.x.x

You need a working wi-fi internet connection on your Iphone or a working internet connection on Itunes with your computer to restart the phone properly. Apple requires that the phone or itunes check back with their servers.

You can't restart the phone properly with only a 3G or 4G data connection using tethering and a laptop or the phone only.

If the phone is already showing the normal icons etc you have a different problem.

If you have normal icons showing on the phone make sure you are using a usb cable to sync rather than a wi-fi sync for the first sync

iOS 6 requires iTunes 10.7. Did you update iTunes on your computer?

I'm having the same problem. I have iOS6 and my itunes was updated to 10.7. Unfortunately, i can't sync my phone now. Please let me know if you we're able to fix yours.