How to Change Your Theme to Default If You Can Access WordPress

1. Navigate to the wp-admin directory of your website and log in to the WordPress dashboard.
2. Go to 'Appearance' to load the 'Manage Themes' screen. To change your theme back to the default theme that came with your copy of WordPress, find the theme and click its 'Activate' link. The naming convention for default themes since WordPress 3.0 is the release year spelled out in words, such as 'Twenty Ten' or 'Twenty Eleven.'

3. Click 'Add New' on the 'Manage Themes' screen to search for the original copy of the default theme if you made changes to its code. Type the name of the theme in the search box and press 'Enter.' Click the 'Install' link under the theme and click the blue 'Install Now' button on the pop-up box. Wait for the theme to finish installing and then activate it to set it as your current theme.
4. Search for a theme that you want to return to default settings if you changed its code. Install and reactivate the theme. If the theme did not come from the free listing provided by WordPress in the dashboard, click 'Upload' on the 'Install Themes' screen instead. Select the original zip file you downloaded for the theme and upload it to begin its installation. Install and activate as usual.