I am guessing that your overwrote your file with a blank datebook. I avoid
this by renaming each of my standard apps documents to a personal name, ie.
datebook renamed to mydates. The downside is that I either have to start
them from the File Manager or enter the app and switch documents. Each time
you use the launcher or the express menu, it opens the default document, ie.
datebook. If you don't have one, ie. you renamed yours, it creates one.
This is why I use file manager to launch.
This may have restated the obvious, if so sorry.
Rusty