you will have reset urls in Settings General
follow this steps
If you have access to the site via FTP, then this method will help you quickly get a site back up and running, if you changed those values incorrectly.
1. FTP to the site, and get a copy of the active theme's functions.php file. You're going to edit it in a simple text editor (like notepad) and upload it back to the site.
2. Add these two lines to the file, immediately after the initial "<?php" line.
update_option('siteurl','http://example.com/blog');
update_option('home','http://example.com/blog');
Use your own URL instead of example.com, obviously.
3. Upload the file back to your site, in the same location. FileZilla offers a handy "edit file" function to do all of the above rapidly; if you can use that, do so.
4. Load the login or admin page a couple of times. The site should come back up.
5. Repeat the above steps, but remove those lines. IMPORTANT: Do NOT leave those lines in there. Remove them immediately after the site is up and running again.
once you got your website back and you still want to change your urls then you can change the both urls but do not try to go on your website as you will get error.
Log into ftp or server and move all files and folders from wordpress folder to root and then go on your website.
You will need to go in permalinks and reset your permalinks.