Login to your account
Enter your username and password and login to your Tumblr account first. Then click on the name of your blog to open it. There will be an option of ‘Custom Appearance’ on the right side of your window, click it to enter the page where you can see your respective blog’s layout.
Set the appearance to default
When you have entered the ‘Custom Appearance’ page, there will be a menu on the left which shows different options to alter your account. Amongst the options there will be an ‘Appearance’ tab. Click on it to make changes to the appearance of your Tumblr account.
Reset the settings to the default mode after entering the ‘Appearance’ tab. There will be an option of ‘Reset Defaults’ which will be displayed prominently on the page. This will automatically change the settings to the default mode and will delete any changes you have made since making your account.
There will be another option of ‘Description’ in the Appearance heading. Click on the tab to enter the field. This will contain a Description box which contains an HTML code in accordance with your Tumblr Layout. Empty the Description box to delete all the customizations you have made over the period of time. ‘Save changes’ in the end to continue with the default settings.
Click on the ‘Themes’ tab on top of the bar to make any new changes to your layout.