LAN or WAN IP? Very different steps, please state.
LAN: In the internet settings on your computer, select "IP address" and change it, leave the first 2 blocks (Separated by the periods) the same but change the last two (E.G. if it was: 192.168.0.1, you can change it to: 192.168.1.0 or 192.168.5.8, but not 192.164.0.1 or 195.168.0.1), then, restart your connection to the router.
WAN: First try turning off the router for 60 seconds then turning it back on, if this doesn't work, try leaving it off over night, if that doesn't work, try resetting to factory settings (Works for me), although, if you want to act as though you're in a different location/country, you have to use a "VPN", which means "Virtual private network". I recommend "NVPN", they're fast, log-free (If you want to do other illegal stuff I won't go into), located in 5 different locations and most importantly, cheap. (I recommend the monthly dedicated IP, I'm from the UK so I use the Netherlands package. I use it 24/7 and I get NO lag in FPS games).
Too lazy to proof read, get-at-my-grammatical-errors-/b/roski.