If you by accident delete a deal, you can easily recover it by following these simple steps. Deal will just have changed status to "Deleted" and by creating and applying filter you will be able to see ticket and reactivate it.
To see all deleted deals open the workflow where deals(s) are located and select filters. Create custom filter and under "Status" options select "Show archived instead of open Deals".
Then open deal you would like to recover, go to Deal Actions button and from drop-down select "Open". Deal will be restored to stage were it was marked as deleted and found with other active deals.
You can do this for multiple deals and recover as many of them as you need. When finished just close applied filter and you will be brought back to your active deals.