The default Tumblr theme is called Redux. If you have changed your theme, you can restore the original Redux theme via the Tumblr Theme Garden repository or the theme’s details page, by reverting to the original theme using the Tumblr Theme Recovery tool, or by copying and pasting the original HTML code if you had the foresight to back up the original Redux code before editing your theme.

The Redux Theme

The Redux theme was introduced as the original Tumblr theme with the official roll-out of the platform in 2007. When a blog is first provisioned on the Tumblr platform, the Redux theme is applied to the blog by default. The Redux theme includes Tumblr features such as integration with the Disqus commenting tool, social media integration and localization.

The Redux theme displays the Followers and Following tabs on the blog’s dashboard once you acquire one or more followers and follow one or more blogs. The theme also displays Queue and Draft tabs in the dashboard if you have any posts saved in your Queue or Drafts folder. You can change the background colors, the theme images and other features of the Redux theme without changing the theme.

Though the Redux theme is the original Tumblr theme, you can apply one of several other Tumblr themes, as well as install custom themes, to change the look and layout of each of your blogs. You can also customize Redux by directly editing the theme's HTML code.

Theme Garden

The default Redux theme is listed in the Theme Garden. Open the Customize menu for the blog you want to restore to the original theme, click the “Browse Themes” link, select the Search icon when it appears, and then type “Redux” in the Search box. When the Redux thumbnail appears, click the image to preview the theme. To apply the theme, click the “Use” icon. Click “Save” to save the theme, and then click “Exit” to close the Customize menu.

Theme Details Page

Install the Redux theme directly from the theme details page. Open the details page for the Redux theme by typing the URL of the details page directly in the address bar of your browser, and then pressing "Enter" while logged in to Tumblr (see Resources). Click the “Install” icon on the theme details page, and then click the blog to modify in the pop-up dialog box to install the theme to the selected blog. Click “Preview” to view the theme before installing.

Theme Recovery Page

The Tumbler Theme Recovery page records up to 20 iterations of theme changes for your blog. To access the Theme Recovery page, log in to your Tumblr dashboard, type the URL for the page in the address bar of the browser (see Resources), and then press “Enter” to open the page. Click the “Choose Blog” drop-down box, click the name of the blog to view in the tool, and then click “View Backups” to see a list of backups. Click the “Show Changes” link next to a change entry to view the backed-up theme, and then click “Revert” for the selected entry to restore the theme. Note that no confirmation box appears, so once you click “Revert,” the theme is instantly changed.

Copy and Paste Original HTML Code

It's a good idea to always back up your Tumblr theme's HTML code prior to editing the code. If you made a backup of the original Redux theme in a text file, select all of the code in the file, and then press “Ctrl-C” to copy the code to your clipboard. Open your Tumblr dashboard, click the “Customize” tab for the blog to modify, and then select “Edit HTML” to open the HTML editor. Select all of the code, and then press “Delete” or “Backspace” to remove it. Click inside the empty code box, and then press “Ctrl-V” to paste the backed-up HTML. Click “Update Preview” to view the changes in the Preview window, and then click “Save” to save the theme.