You can get onto client care and ask them to restore it. There is also a hack...
(you need to be an admin)
access the usage logs, and search for the workspace project name (expand time range as necessary until you find it). In the log entry you will see the project name and alongside it the project ID. Copy this ID to clipboard.
Next go to workspace and open any project. In the URL you will see at the end a long string of chars and nums. Remove this and replace with the copied ID above. Press enter.
your “deleted” workspace project should now load. You can then Save. You will need to reshare and reschedule.