How to enable Search Widget/Gadget

If the the Search widget or gadget of your Blogger blog is not working but the embedded search box on the Navigation bar at the top is working, the cause could be the setting of robots.txt.

1. View the robots.txt at http://YOURBLOGURL.blogspot.com/robots.txt. If Disallow property is set to /search, search is ignored.
2. Go to Blogger Dashboard > Select Blog > Select Settings tab > Search Preferences
3. Enable Custom robots.txt
4. Copy the content of current robots.txt but set the Disallow property to blank.
5. Save changes