As long as you ain't using the hd (like surfing the net, defragmenting, copying and so) the files should still be intact. Otherwise, you got a big probability that the files are damaged (by partially overwriting it or so).
If the latter is the case and these files are extremely important, you can send your hd to the manufacturer or so wich have special instruments to recover overwritten files.
But sorry, I do not know atm a name of a recovery program.
