If you've registered it you can find the serial if you login here: https://supportprofile.apple.com
Good luck finding it!
Next time asking a question here. Remember to put it in the right category. This is the iPhone section.
1. This is the iPhone Forum. Completely independent to the computers forum which can be found here:
2. This is a 2 month old thread, why not create a new one in the correct forum category for your problem instead of hijacking someone elses?
3. Unless you set up the Find My Mac service on it, there's no way to track it. Contact your local police and start an inquiry with them.
The serial number can be used to determine ownership by the police of they find it.
If you did set up Find My Mac, you can lo into iCloud.com and try to track it from there, if its turned on and connected to a wifi network.