Recently I accidently deleted an object from the Objects List in the Creation Kit instead of deleting an object in my plug-in. Now every time I try to place it I get the error message "Object '...' has been deleted."

How do I restore this file?

Me too! I was trying to delete a piece inside my preview window, but the window must not have been active.

Undo the changes by going to the Details section of the Data Files window.