well to completely remove data is a zero fill, it erases the file header then prints 0s over every bit/byte of the file. Did you save anything on the drive again? or install an OS on it? If either of things occured, the data is not recoverable. If not you can get data recovery tools for varying costs which will attempt to recover as many files as possible, by re-instating the file headers. The more fragmented the drive was, the harder this will be. It can be done, a friend did recover 40% of his files from a drive he mistakenly erased.
*There is no real hacker, who would call themselves one. Be careful about all information you recieve, heck even here you need to be just a little skeptical.