Well, formatting won't make the formatted files deleted permanently because when you formatted the hard drive, you simply rewrited or updated the FAT table or NTFS table which manage all the data storage process.
If you are using lower Windows OS, you can use the command "unformat" to unformat the files you have deleted.
If you are using some higher Window platforms, the best way is to try some format recovery programs. Try this one to see if it will help? http/www.disk-utilities.com/data-recovery/format-recovery.html
One more tip: before your formatted files are recovered, better not save more files to the disk in case rewrite the original data.