This articles explains how you can recover deleted sessions. 

How to Manage Deleted Sessions:

1. In the Settings tab, navigate to Appointment Setup and click on Deleted Sessions. 
2. Select the relevant date range.
3. Select the patient(s).
4. Select the provider(s) if needed.
5. Click Go to generate the deleted sessions.
6. To revert deleted sessions, select the necessary sessions by clicking on the checkbox, choose the revert option from the drop-down field, and click on Go.