If the external IP address was changed, it was most likely changed by your ISP and no action on your part is required. This is typical and the IP could change at any moment. If your internal IP was changed (something like 192.168.1.1), my suggestion is to set it back the way it was and strengthen your login/pass credentials to get into your router.
May 14, 2007 How do I Change my IP Address (IP Banned)? | www Infopackets Reader Elaine Y. writes: " Dear Dennis, How can I change my IP address? I ask because every now and again I try and email my friend (with a yahoo email address), but Thunderbird keeps telling me that my IP address is being blocked and can't send my email. Any ideas why I'm being blocked? Better yet, any idea on how I can change my IP address so I'm not blocked? My IP has been the same for months : VirginMedia
FIX: Local IP address changed, can’t log in to WordPress
Jan 30, 2018 Default Gateway: Changed to "10.0.0.1" - NETGEAR Communities
How To Change My IP Address Permanently In 2020
How to change IP address of my network – OpenDNS Where