Changing it the way Krishubpages123 says will NOT work, because this only changes your local IP address and you need to change the EXTERNAL IP Address!
To change your External IP Address, it kind of depends what type of Internet you have. Most types of Internet have Dynamic IP Addresses, which means that they will change periodically. However, some change more frequently than others.
If you have DSL, then your IP Address will likely change rather frequently, but you may be able to hasten it by resetting your modem.
Often with Cable Internet, the IP Address is linked to your Mac Address. So, if you connect to your modem with a different MAC Address, the IP may change.
If you have a router, it is usually fairly easy to change, or spoof, your Mac Address, which will cause you to get another IP Address. However, it may just be easier to plug a different computer directly into the Internet, because each computer has a unique Mac Address.
Regarding reporting him, if you know HIS IP Address, you can report the intrusion to his Internet Service Provider. Otherwise, you may be best off contacting your Internet company, but keep in mind without proof, there may be little they can do.