When an unfortunate situation, such as scenario deletion, happens, there is still a possibility to restore it via UI by following the steps below:
Navigate to Campaigns > Scenarios tab, and click on the highlighted icon
This action will bring up the general Scenarios History, where you will see actions taken by users for all scenarios in the project.
Locate the Deleted [scenario name] action in the Scenarios History
Doing so will also allow you to see the user's name, date, and time of the deletion.
Click on the Deleted action in Scenarios History - will open the last version of the deleted scenario
Save the last version of the deleted scenario
You can choose whether to replace the version or create a copy.
Both actions will restore the deleted scenario.