How To: Protect the DEFAULT version from accidental feature deletions
When editing ArcSDE layers in ArcMap, features that are deleted from the DEFAULT version cannot be recovered after a save is performed. Even though these deleted features exist in the Geodatabase's 'D' table, there is no current method to restore them. This article offers two suggestions to protect the DEFAULT version from accidental feature deletions.
In ArcMap, create a version off of the DEFAULT version that can serve as backup. Create additional working versions for making edits. If you need to restore features after saving the data, simply copy the deleted features from the backup DEFAULT version and paste them into the current working version. This will leave the original DEFAULT version untouched and in its original state. You can then post the edits back to the original DEFAULT version as needed.
In ArcCatalog, you can create 'protected' privileges on the DEFAULT version. You must be logged into ArcSDE as the SDE user to accomplish this. Protected privileges will allow any user to view the DEFAULT version, but only the SDE administrative user has the ability to post and make edits.
For more information about versioning, see Chapter 11 of "Building a Geodatabase" by Andrew MacDonald.