NVivo: Why is Undo greyed out and how can I recover older versions of my project file?
Go to the Save and Recovery tab of File->Project Properties: If Autosave is set to Yes, Undo is disabled. You can disable it. Once you do this Undo will be usable and you will be prompted regularly to save the project file. The timeframe is configurable in the same window (Default = 15 mins) If you are only storing one recovery file at a time under the Project Recovery section, the last saved version is all that is accessible. Change "Store the most recent" files value to a number greater than 1 to allow for version recovery.