Use this wizard to restore accidentally deleted partitions.
Right click on the Unallocated Space (smaller rectangle with Free label) inside a disk and select Undelete partition.
Specify the search algorithm. Usually Quick Search is enough, but Scan All Sectors mode is more thorough (and slower).
Press Search to begin the search operation.
List of found partitions will appear after Search is completed, allowing you to choose partition you wish to restore.
Select the partition you wish to restore and press OK to begin Undelete operation.
After the operation is completed, you should see and be able to access the restored partition.
Hard Disk Manager for Mac, HowTos: Mac OS X, Products for Mac OS X
Tags: HDM for Mac, mac, partition, undelete