Deleted or missing Theme Builder templates can be restored with the help of a specialized WordPress plugin Divi Restore Theme Builder Templates
Install the Divi Restore Theme Builder Templates plugin
Click the following link to download the plugin installation zip file to your computer:
https://github.com/eduard-ungureanu/restore-missing-tb-templates/archive/refs/heads/main.zip
(NOTE: Safari users should disable "Open safe files after downloading" option in General settings of the browser)
Install the plugin zip file by following these steps:
1. Log in to WordPress Dashboard and go to Plugins > Add New
2. Click the Upload Plugin button
3. Click Choose File button and find the location of the downloaded main.zip file
4. Click Install Now button to install the plugin
5. Activate the plugin
How to restore Theme Builder Templates
After plugin activation, we will see three new links in the WordPress dashboard menu:
Header Templates
Body Templates
Footer Templates
Each of those links leads to a listing page where you can see what layouts can be restored:
Edit and Save the chosen template to Divi Library
Click the name of the template in the header/body/footer Templates list and it will open as an editable Layout in Divi Builder
Click the Save To Library icon in the Page toolbar
Name the layout for the Library and click Save To Library to save it
Import the saved (restored) layout in a Theme Builder header/body/footer
To use the Divi Library layout we just saved:
Go to Divi > Theme Builder and click Add Global Header/Body/Footer
Choose and click Add From Library
When Divi Library opens click the Saved Layouts tab and then click the name of the layout we restored
Click Use This Layout button
After import click the Save Changes button
Note: Once the layout is restored, please deactivate and delete the plugin from your website.