It depends.
If you have dialup via a modem or PPPoE DSL, your IP changes every time you log in To change it just sign off and redial your connection.
If you have a static (unchanging) IP service like most cable modems, you would need to call your ISP's tech support and ask them to change it. Internet IPs are owned and distributed by the ISP, and only they can change and control them. Contact their tech support and request a change.
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