Search your system for these two files;
bookmarks.html and bookmarks.bak
If you find them, double click on the bookmarks.html file, and this will open in your default browser as a list, (tree), of bookmarks. That can tell you if your existing bookmarks listing has been corrupt, or if it is something more serious with Netscape.
If the listing is corrupted, copy that bookmarks.bak file to somewhere save, then rename the extension on the copy to html. Double click the copy. This is the backup of bookmarks.html, and it will also open into your browser listing your bookmarks. If that is not corrupted, then you should be able to delete the original bookmarks.html file, rename the original bookmarks.bak file to bookmarks.html, and see if that works.
I can't help with the AOL problem, sorry.
Following a simple RAM upgrade install, I noticed my some of my bookmark main folders were either missing or misplaced and shuffled into other bookmark folders. Some were also duplicated. I also noticed when rebooting AOL the following error message: The main.idx database file is damaged. Error: 65-FONL. I don't know if either of these have anything to do with my bookmarks getting messed up, but I've never had this happen before.
Can bookmarks just dissappear or can they be retrieved somehow. Please advise.