It may be possible to recover some erased ones, but you must quit using the Computer immediately, because the OS will think it can write to those freed blocks on the disk.
Either boot this one in Target mode...
And recovering from another Mac, or booting this Mac from another HDD, then using Data Rescue...
(Has a Free Demo to see if it could or not, but you'll need another drive to recover to).
Or professional Data Recovery Services.
BUT, every second you use that Mac the chances will be slimmer.
rccharles on file recovery...
"Stellar Phoenix Macintosh - Mac data recovery software, recovers data from damaged, deleted, or corrupted volumes and even from initialized disks."
They have a trial version, so I guess you can see if your data can be recovered...
FileSalvage is an extremely powerful Macintosh application for exploring and recovering deleted files from a drive or volume. FileSalvage is designed to restore files that have:
* been accidentally deleted.
* become unreadable due to media faults.
* been stored on a drive before it was re-initialized/formatted.