First, make sure Ardour isn’t running. As a safety precaution, rename your session files, or move them to another folder. Then, copy the *.bak files to the original session filenames. For example (Linux shell):
Or perform the equivalent steps using your file manager.
You will lose any changes made to the session since the last backup was created, but if the trouble is only with the session files, then you should be able to recover most of the session.
Thank you, Dennis,
I followed that procedure, but for some reason when I execute the file Ardour freezes (it opens the “splash” image and then stays still there for ages).
It would be helpful if you could provide information on console messages, and if possible a backtrace, so that whatever issue you are running into can be fixed for yourself and others. See… http://ardour.org/debugging_ardour.html