I ran into an issue this week where I switched on SSL on a development site and then realized the SSL cert was not installed correctly. This is a big issue in Magento because there is no way to get back to the admin to switch it back off.
If this ever happens do the following to switch back:
1. Open up your admin panel (cPanel or other)
2. Go to phpMyAdmin (if MySql)
3. Find your Magento Database
4. Find table “core_config_data”
5. Look for the columns “web/secure/use_in_frontend” and “web/secure/use_in_adminhtml”
6. Edit both values, make them equal to “0”
After this is done you will be back in action.