Lightroom: Step backward in library module?

Try undo.

Wont work. It is only for the most recent change.

Undo is for a very long list of anything you've done pretty much since you opened the application.

How do I do that? When I try edit>undo it is greyed out.

I just use control-z.

Braden, when you close LR, the undo history is not kept for a future session. You can only step back regarding what you did in your current session. This might explain why you cannot undo your accidental change of flags.

If you have the Lightroom preferences set to the default settings, Lightroom is saving a backup of the catalog once a week. It saves it to:

user/Pictures/Lightroom/Backups

You could replace your Lightroom catalog (located at user/Pictures/Lightroom/Lightroom 3 Catalog.lrcat) with the most recent backup. If the backup was made before all the flags were accidentally deleted, then reverting to the backup would bring back all your flags. Of course ALL changes that you'd made since the time of the backup (not just the deletion of flags) would be lost.

Having said all that, I would advise you not to mess around with trying to replace your Lightroom catalog unless you're confident you know what you're doing, and have safely backup up all your data. :-)

-Ben