Hi iael,
If you rename the WordPress directory on your server, switch ports or change the hostname http://codex.wordpress.org/Moving_WordPress applies. Follow the instructions on that link to properly change your site URL.
WordPress often stores serialized data which will break when a simple find/replace is ran on the domain string itself. The search/replace script by interconnectit (you can find a link to this in the moving wordpress link above) is my preferred method of doing this.