Update permalinks after domain change

Option A: Here’s a Quick Way to Search and Replace Your WordPress Database

Option B: Export your database using phpmyadmin and open in a text editor such as (Notepad++), and use search/replace to find old domain and replace with new domain.
MAKE SURE YOU BACKUP YOUR DATABASE BEFORE TAKING ANY ACTION

404 Not Found

Not Found

The requested URL was not found on this server.

Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.