This guide requires no fiddling around or downloads and takes about 1 second
I was compelled this guide because my friend was banned for hacking and I helped him out. Now I will tell my buddies from MPGH!
I also saw the other guide but it does NOT always work
Copy the following into notepad:

Echo ipconfig/flushdns
ipconfig/flushdns
echo ipconfig/release
ipconfig/release
echo ipconfig/renew
ipconfig/renew
exit

Then save it as ipchanger.bat the name doesn't matter only the bat extension so cmd will open it.

Open the batch file and your ip should be changed tada!