Need HELP! recovery for erased partitions

[3rdgen]

Need help. i have 160gb seagate external hd. It has 3 partitions , 7mb , 75gb and another 75gb ( ntfs formated in windows ). I inserted it to my MBP via usb, and try to erase the 7mb partition in disk utility, since i cant format it via windows, what happened was, the other 2 partitions were also erased! tried opening in windows but its gone! Partition magic says it's unpartitioned disk. All my works are there, is there a way to recover the files? Is there a recovery software? Please help, thanks!