Error 404 after changing URL

Access phpMyAdmin on your host, then check the wp_options Table (Note: The table prefix of wp_ may be different if you changed it when installing), and make sure siteurl field and home field are correct. See https://codex.ww.wp.xz.cn/Changing_The_Site_URL#Changing_the_URL_directly_in_the_database

You are welcome 🙂

my links show Error 404!

By “links” do you mean permalinks?

If so, try resetting your custom permalinks back to the default setting and renaming your WordPress .htaccess file. If that works, then try reading Using_Permalinks before setting a custom permalink structure again. If clearing your Permalinks does not alleviate the issue, this could be attributed to anything from a web server configuration to a bad WordPress install.

You are welcome 🙂