Crashes can wreak havoc on your client. I would start by compacting your desktop. You have to go to the workspace to do this in R5. If that doesn't bring them back, close Notes, and then delete the cache.dsk file, which is in your data directory. Restart Notes, and it will be recreated. If that doesn't bring them back, simply find the bookmarks for the missing databases and drag/drop them back onto the Replicator tab.
This was first published in February 2001