How do i undo an IP Address change?

If this has been posted before im sorry i tried searching it on google and on youtube and on here but i got nothing so i was wondering if there was any way to undo an IP address change. i used fast ip changer 1.7 and i changed it cuz i was ip banned from CA but now i cant acces the internet plz help

Edit: u wont believe this but....
i prayed.... and prayed...and searched and searches and prayed some more........ then i found out the answer plz close this thread