configure oracle db on windows

I have an oracle instance on VM Player. It is running on Windows 2003 server. It was working when the virtual machine is on different network. Now, I changed it to NAT-network in VM Player and the IP has changed. The oracle instance not working with the new IP. I tried to configure the [login to view URL] nad [login to view URL] but I couldnot succeed. I think it is an easy job for an Oracle user, but I am new to oracle... The job is to make the oracle instance run on new IP configuration without changing the NAT configuration of the VM Player.