Justin Tadlock

Ever had a widget get stuck in a particular sidebar or widget area? Are your widgets missing when you switch themes?
This plugin will remove all widgets, setting everything back to the factory settings.

Widgets Reset

Allows you to reset all of your widgets, wiping the slate completely clean.

FuzzGuard

This plugin allows you to display widget items based on if a user is logged in, logged out or based on the role you have given the user.
This plugin allows fine-grained permissions to be added to each individual widget item to display or not display the item based on the 
 users logged in/logged out status or the role assigned to the user. This solves the problem of having to modify theme functions.php files to add in widget restrictions. The changes in functions.php is often overwritten by a theme update. This plugin removes that worry, as you can update the theme, independent of the plugin.

Privilege Widget

This plugin allows you to display widget items based on if a user is logged in, logged out or based on the role you have given the user.

Widgets Reset vs Privilege Widget