Hello Anna,
Thanks for your question about editing the site URL. If you are not able to access the WordPress Dashboard, then you will need to gain access to the WordPress core files. There, you can to attempt to reset the site URL to what it was before you made the edit. This change can be made in the `wp-config.php` file, which will be present in the root directory of your WordPress site.
This issue falls under the category of general WordPress troubleshooting that your host can assist with if you have any trouble.
Best,
Christopher M.