You can activate logging in Plan-IT. When this option is enabled, all important events are kept in the logging of Plan-IT. This way you can find back what exactly happened in the planning. And maybe even more important: by which user certain actions have been performed.
Follow the below steps to activate the logging:

Because this is a global setting for all establishments in Plan-IT, you need Master rights to turn this on. (Keep in mind that after turning on this option, Plan-IT will log all actions and save them in a logging database. This can cause Plan-IT to be performing a bit slower. With a fast network speed, the difference in speed should be minimal).
When you click with the right mouse button on a work order now, the contextmenu has the extra option Logging:

Click on the Logging option to open the om het Logging window. Here you can find everything that has happened with the work order:

The logging window shows an overview of everything that has happened with the work order. This way Plan-IT will keep track of whether an appointment confirmation e-mail has been sent (and to what e-mail address) whether connections have been succesfully made, when a work order has been moved or modified, when a work order has been deleted.
To check if a work order has been deleted, open the logging of another work order and enter the work order number of the work order you are looking for in the field that is in the top of the screen, and press the <strong "="" data-redactor-tag="strong">Enter key. This way you can easily check the logging of work orders that no longer exist in Plan-IT. You can also see which user has deleted the work order:

Keep in mind that Plan-IT will only start logging from the moment that the logging option is activated. You can not view any logging from the past when the logging was not yet activated.