if you want to change your lan address then go into the command prompt and type:
ipconfig /release
once that's done, type:
ipconfig /renew
if you want to change your WAN address, the easiest way is to unplug your router and modem for like 20 minutes then plug them back in.
Another way is to take the cable that goes from the modem into your router and plug that into your computer. Then do the ipconfig commands mentioned above. then plug the cable back into the router.