If the data you are using in Informant is iOS/iCloud based then you will need to restore the data to the devices stock calendar and reminders apps before it can again be visible in Informant. Apple support can help you to restore the data to your stock calendar and reminders apps.
Once the data is visible in the devices stock calendar and reminders apps you can bring it into Informant by going to the device settings, privacy and moving the Informant slider to the on position. Repeat for reminders and contacts.
Then in the Informant settings, sync accounts, move the calendar app and reminders app sliders to the on position and the data should be visible in Informant.
If you are using Exchange data with Informant the same rules apply as when using iOS/iCloud data. The Exchange data will need to be restored to the devices stock calendar and reminders apps before it can be seen in Informant.
No iOS reminders or events are backed up in Informant and will not be restored when restoring an Informant backup file.