If you edit the secure/unsecure base url for you Magento based site you may find yourself locked out of both the frontend and admin sections of the site.
To solve this problem take the following steps:
- Log in to your database using phpMyadmin or similar.
- Find the table labelled core_config_data
- Edit the rows entitled web/unsecure/base_url and web/secure/base_url
- Edit the row web/url/redirect_to_base to 0 instead of 1
- Using your ftp client clear contents of both var/cache and var/sessions folders.
For more info on base urls for magento click here