Lost Partition

So I have a MacBook Pro, with a 500 GB hd. I had 3 partitions: Mac Lion (100 GB), Mac Snow Leopard (100 GB), and Data (300 GB). I was running out of space on my Lion partition, and Snow Leopard is just an empty partition, so I decided to delete it and resize my Lion partition. It wouldn't let me delete the Snow Leopard partition, so I just gave up.

I didn't notice any side affects (this was a few days ago), but my laptop battery just died a few hours ago. I didn't think anything of it, but after trying to open iTunes, I realized my 300 GB Data partition is nowhere to be found. When I open disk utility, it shows Mac Lion (100 GB), and disk0s4 (299 GB) then no partition in the last 100 GB or so.

The disk0s4 partition isn't mounted, nor can it be mounted. Is there anything I can do to recover the data that was on my Data partition though? Nothing's been mounted over it, so I'm pretty sure nothing has been able to modify it so far.

Thanks,
Ryan Pendleton

 

I tried verifying and repairing in Disk Utility, as well as the application mentioned in your post. Neither worked.

I'm not exactly sure how partitioning works, so I may be wrong, but I think what happened is the partition table got messed up when trying to delete the partition, but Mac didn't reload it. That's why I could continue to use the partitions, but they disappeared after a reboot.

If the above is correct, then I think I can recreate the partition table, and get the volumes back with little, if any data loss. I was using gparted, but unfortunately, it was taking longer than I thought it would and I didn't have enough time to let it finish. Does anybody know how long gparted usually takes? By the time I had to stop, it had been running for 2 or 3 hours on the "Searching for File Systems" step.

 

So I tried Data Rescue 3, and Drive Genius 3, and neither of those worked, even deep scans. So I guess i'm stuck with having to redo the partition table. Supposedly, people have fixed their partitions using gparted or something similar, but it will take a long time.

The thing that is bugging me the most, is the fact that I know my data is still on my drive. (at least a majority of it) because I had been accessing files and changing them after the partition table got messed up.

I'll let you guys know what happens with gparted or whatever I end up using in the end.

Update:

So I ended up using something called testdisk. It scanned my hd and found 15 partitions, and rewrote my partition table using them. None of them were the partition I was looking for, but I'm glad to know this tool is there for the future, some people have had success with it.

So I think my next step is going to be guessing the partition map I had before. I know the exact size of each partition I had, so I may use the "parted" utility to search for a partition in the know space, using the rescue tool. So far though, I think I may be hopeless getting my data back.