Select File»Revert to return to the last saved version of the VI you are editing. A dialog box confirms whether to discard all changes made to the VI.
VIs modified since they were last saved have an asterisk in their titlebars and in the list of open VIs displayed in the Window menu. When you save a VI, the asterisk disappears until you make a new change.
You also can use the Revert VI method to return to the last saved version of the VI programmatically.