We do NOT recommend to change domain or WordPress URL. We understand, that sometimes it is necessary. In that case:

  1. Do backup MySQL and whole WordPress directory.
  2. Check backup once again (You must be sure that everything is backed up, really).
  3. Go to WP Admin.
  4. Replace page url from /wp-admin/ to /wp-admin/options.php
  5. Find there options home and siteurl and replace values to the new right values – new WordPress URL
  6. Press Save on the page bottom.
  7. You will have to change images path in pages, posts, portfolio posts and options.