Formatting won't make the data in the hard disk erased permanently at the moment, I think. Those formatted data are still stored on the disk just invisible or inaccessible. Only the FAT or NFTS table erased the information about where those data were saved but the real data are still intact there in sectors of the disk.So as long as those data are not overwritten by new data, it's highly possible to recover them. And the MOST Effective way is to rely on some file recovery software
or more specificly some format recovery
programs to get them recovered.
Be careful, before the formatted data are recovered, better not put more data to the drive.