If your menu items have disappeared from the Appearance > Menus panel, this means that they have been deleted from the database. This doesn’t just happen spontaneously, it has to be triggered by something.
Remember, menu items are created and stored by WordPress core in the WordPress database; UberMenu does not alter this process, it just stores extra data for these menu items. Losing menu items is not an indication of an issue with UberMenu. It is almost always indicative of a PHP configuration issue with your server
Double check you’re viewing the right menu
The first thing to check is that you are viewing the proper menu in Appearance > Menus. Remember that you can create multiple menus the Menus panel. Ensure that you are viewing the proper menu, that it is assigned to the appropriate Theme Location, and that that Theme Location is activated for UberMenu.
Menu Item Limit – items lost upon menu save
If your items are lost after clicking Save on the Appearance > Menus Panel, there is a very high likelihood that you are experiencing a Menu Item Save Limit. This is an issue with your server configuration, and not something that UberMenu can control. Fixing the issue can be pretty simple, but the menu items can’t be recovered unless you have a backup.
This article describes the menu item limit issue, which affects WordPress menus with or without UberMenu, in extreme detail.
Database corruption
It is possible, though very rare, that you may have some type of database corruption. This might occur if another plugin/theme mistakenly deletes data from the database, or if you have some sort of infection/malware on your server that has corrupted your database tables. There is a slight possibility that running a MySQL database repair may help. You can speak to your server admin regarding how to run that process.
While this is very rarely the case, it is something worth considering if you have ruled out the Menu Item Limit issue.
Can I recover the menu items?
If your items don’t appear in Appearance > Menus due to a Menu Item Save Limit scenario, they have been deleted from the database and no longer exist. If you don’t have a database or server backup, there is no way to recover them.
Database backups
If you have a professional webmaster running your site, they are almost certainly running nightly or at least weekly backups of your database. In this case, recovering your menu items is as simple as restoring the most recent database backup from before the items were deleted. This will revert your site to its state at that point in time.
If you are not running backups on your WordPress site, you should start now. It’s very simple. One easy way to get started is with the Backup to Dropbox plugin.
Server backups
If you haven’t been backing up your database, you may have server image backups. Depending on your host and plan, this may be something you/your server admin has set up, or it may be something your hosting company does automatically. If there is a server backup, you can restore to that point in time, as it should contain a database snapshot as well. After restoring a backup, don’t forget to properly configure your server so that the issue does not recur.
This is something that varies widely from host to host, so you’ll need to discuss it with them or your server administrator.