There are some programs that might help you, IF you are lucky and the data hasn't yet been permanently destroyed (a delete only removes a file information block in the index of the drive, but if the actual data has been overwritten it's unrecoverable).
Another reason for backing up your stuff regularly :)
Its "shareware" but does have a free trial. The problem is, as you add new data to your hard drive you risk overwriting the file. And installing a utility to recover your file might just overwrite it. But I guess you really have no choice.